Crinoids, Belonging to the Families Antedonidae and Atelecrinidae

RECENT UNSTALKED CRINOIDS. 129 NOTE XXV. Descriptions of twenty new recent unstalked Crinoids, belonging to the families Antedonidae and Atelecrinidae, from the Dutch East Indies BY Austin+H. Clark The work of the the steamship »Siboga” among islands of the East Indian Archipelago resulted in the discovery of of unstalked many new species crinoids. In view of the amount of in and large work necessary assembling digest- the data ing accumulated on these, and especially on the species already known, it has seemed advisable to publish in advance preliminary diagnoses of the new forms in order to guard against possible anticipation. In the the present paper new species belonging to the families ANTEDONIDAE and ATELECRINIDAE, including among them the most striking of those collected by the »Siboga”, are considered. All of the new species will be described in greater detail and figured in the final memoir on these animals in the »Siboga” series 1). Family ANTEDONIDAE. Antedon moluccana, sp. nov. The centrodorsal is low hemispherical, the bare dorsal with rounded pole very slightly convex an obscure broadly median tubercle surrounded by obsolete cirrus-sockets, 1.5 mm. in diameter. See for the of the Nos f the various 1) explanation 0 page 156. Notes from the Leyden Museum, "Vol. XXXIV. 9 130 RECENT UNSTALKED CRINOIBS 15—17 the The cirri are about XXX, (usually latter), is the longest about 18 mm. long; the first segment very is and to two short, the second one one half times as median the third is from two and long as the diameter, three the median one half to times as long as diameter; the fourth and following are about four times as long as the median diameter; after the eighth the segments slowly is little if become shorter so that the antepenultimate any longer than broad; the penultimate segment is small, wedge- shaped, about half the size of the antepenultimate; the earlier opposing spine is small, subterminal; the longer with segments are moderately constricted centrally expanded and slightly overlapping ends; the shorter terminal that segments have straighter dorsal and ventral profiles so to become broader just in a lateral view the cirri appear be marked transition at the tip; there may a slightly segment at about the eighth. the of the The radials are even with edge centrodorsal; the incised in the median IBr, are very short, strongly line by a rounded posterior process from the axillaries, about half as long in the median line as on the lateral edge and about four times as broad as the maximum (lateral) in but length; the lateral edges are just apposition basally, at of about diverge from each other an obtuse angle 120°; the lateral the axillaries are edges are concave; slightly the lateral broader than long, very widely separated, edges those of the at about as long as IBr,, diverging approximately a right angle to each other; the anterior sides at to each and are approximately right angles other, are the anterior is nearly straight; angle only very slightly is rounded median produced; there a posterior process incising the IBr,. The ten arms resemble those of Antedon mediterranea; brachial is twice as the first very short, long exteriorly as the interiorly, median length being about the same as the internal length; the internal proximal third is united with the adjacent first brachial, but the distal two thirds diverge Notes frorii the Leyden Museum, "Vol. XXXIV. OF THE SIBOGA-EXPEDITION. 131 almost in a straight line; the second brachial is much all larger, irregularly quadrate. The arms are broken, but the size of the animal is about that of an average A. mediterranea. is Pj 13.5 mm. to 1G mm. long with from eighteen to twenty-one segments, moderately slender, more so than in the other of the from species genus, tapering evenly the base to the delicate the is tip ; first segment not quite so long as broad, the second decreases slightly in diameter and is distally about as long as the proximal diameter, the third is between two and one half and three times as long and the as broad, following are somewhat over three times as long as broad, becoming slightly longer distally; the segments have straight sides and no production of the distal but the outer have edges, very slightly swollen is articulations; P« similar, but not quite so long; P 2 7 is mm. long with fourteen or fifteen segments, much more slender than P,, though the proportions of the P is 5 component segments is similar; mm. long with 3 eleven segments, slender and weak; the segments beyond the second being much elongated; P is 5 mm. long 4 with ten slender segments, and weak, similar to the pre- ceding but more slender beyond the third segment; P 5 6 with is mm. long thirteen segments, slightly stouter than P with slightly shorter segments; P is 7.5 mm. 4 0 long with fourteen similar to P but with segments, 5 slightly shorter segments which have more expanded ends. Type locality. — »Siboga" Station N°. 139. Compsometra iris, sp. nov. This is nearest to but the new species C. serrata, piu- nulars have only moderately developed spinous overlapping edges instead of having these excessively developed as in C. serrata, the brachials have much less prominent spinous overlapping distal edges, and the cirri are stouter and more curved with shorter distal segments. Motes from the Leyden Museum, Vol. XXXIV. 132 RECENT UNSTALKED CRINOIDS centrodorsal is low the bare The very hemispherical, covered with obsolete polar area almost pits representing cirrus sockets. The cirri are XXX, 10—12, 8 mm. to 9 mm. long, is the second strongly curved; the first segment very short, median the third about twice as long as the diameter, about three times as long as the median diameter, the the the fourth about the same length as third; following gradually decrease so that the antepenultimate is slightly the about longer than broad and penultimate as long as third broad; the second and are strongly constricted centrally with expanded ends, the following gradually losing this character and becoming laterally flattened and hence broader in lateral view, the outer segments being nearly of the there or quite twice the lateral diameter proximal; dorsal the is and are no processes; opposing spine large prominent, triangular, arising from the entire dorsal surface of the penultimate segment and directed obliquely forward. The radials are even with the edge of the centrodorsal; the IBr, are short, almost entirely divided in the median line from the well by a posterior process axillary, separated laterally and not in basal contact; the axillaries are about broad with all the as as long, widely separated laterally, sides concave. The ten which are 45 mm. resemble those arms, long, of C. serrata, but the edges of the brachials, while overlapping and projecting, are much less conspicuously spinous and lack the strong longitudinal ridges running inward from each spinous process. is 8.5 with seventeen Pj mm. long or eighteen segments, moderately slender; the first two segments are than third is about twice broader long, the as long as the median diameter, the remainder approximately three times somewhat the as long as broad, becoming longer distally; third and following have slightly projecting and over- distal this character lapping very finely spinous edges, P 4 gradually increasing in intensity distally; is mm. 2 Notes from the Leyden Museum, Vol. XXXIV. OF THE SIBOGA-EXPEDITION. 133 with eleven segments, much smaller and more slender than two is P,; the first segments are short, the third half again as long as broad, and the following rapidly become elongated; the segments have moderately produced and overlapping spinous distal P is 3 mm. to 4.5 mm. edges; 3 long with about eleven segments, tapering less rapidly than P and stouter, especially P is similar to 2 distally; 4 P but is and the distal 3 slightly longer stouter; pinnules 7 with are mm. long, very slender, sixteen or seventeen segments which have slightly spinous distal ends. Type locality. — »Siboga" Station N°. 144. Compsometra parviflora, sp. nov. The have cirri 8—9 (usually 8) segments and are 4 mm. long; the first segment is about twice as broad as long, the second two to two and one half times as long as the distal the third the expanded end, and fourth are longest, about three times as long as the expanded distal ends; the following slowly decrease in length so that the ante- twice penultimate is about as long as the diameter of its end and is from expanded the penultimate one third to one half again as long as broad; the longer proximal segments are constricted centrally with prominent ends, this gradually decreasing in amount as the segments become shorter distally; the opposing spine is terminal, prominent, to diameter of in length equal nearly one half the distal the penultimate segment. with The radials are even the edge of the centrodorsal, and are slightly separated at their distal angles; the IBr, are half as long in the median line as laterally, about lateral the lateral three times as broad as the length; the edges converge slightly so that adjacent IBr, are widely separated; the lateral portion of the proximal and distal edges is sometimes slightly thickened; the axillaries the lateral twice are rhombic, angles truncated, as broad as long, widely separated laterally. Notes from the Leyden Museum, Vol. XXXIV. 134 RECENT UNSTALKED CRINOIDS The ten arms are from 15 mm. to 18 mm. long; the somewhat brachials have prominent very finely spinous distal ends.

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