4 SVEN LOVEN, ECHINOLOaiCA. 



CToniocidaris caiialiculata Al. At;.'. both liviiig in tlie Aiitarc- 

 tic seas. A third form, tlie highly aiiomalous Anoclianus 

 Gkube-, of tlie China Sea, is as vet but imperfectly known. 



In the Abatus tlie eggs emitted tlirongh tlie sexual aper- 

 tures of the niotlier are reeeived iiito the deep recesses of her 

 petals. Their development lias not been followed through its 

 different stages, but from the fact that Alexander Aoassiz 

 found the marsupiuni replete vvith fuUy developed young ones, 

 and since a spec^imen i once described|was found lying at the 

 very bottom of the petal under a crowded multitude of newly- 

 ejected eggs. it follovvs that the development is performed 

 entirely witliin the marsupium and that no free-swimming 

 pluteal stage exists. The young iVbatus^ measured 2,3 mm. 

 in length, l,<t inni. in breadth, and clearly was not far from 

 leaving the nursery. Its general form is nearly that of the 

 parent. It is still without oral and excretory apertures. The 

 whole body, spines and all, is tightly enveloped with a thiek 

 niembraneous covering, the larval covering. apparently the re- 

 presentative of an abridged and transitory pluteus-stage. With- 

 in this envelope the spines are already strong and the plates 

 of the calcilied skeleton distinct, ambulacral as well as inter- 

 radial. But there are two clear spaces, both overspread by 

 the general covering: the one on the ventral side ])eing the 

 pentagonal stoma of the coronal system, the other, dorsal, the 

 central part of the calycinal system. The intestine is still 

 ccecal at both ends. The closed oral termination touclies the 

 wall of the visceral cavity at the centre of the stoma*. Right 

 över it the excretorial end, in passing towards its future po- 

 sterior position in the interradium 5, moves backwards along 

 the inner surface of the calyx, and causes the calcilied cen- 

 tral piece and the costals to be partly reabsorbed and fractured, 

 while the five radials, each with its still large provisional 

 sucker, remain intact^, an effect of disintegration of the calyx 

 and dorsal part of the test seen to accompany the movements 

 of the intestine during more than one of the phases of phylo- 



' Studer, Berlin. Mon. Ber. Juni lö7(!, j». 455. — Wyv. Thom.son, Yov. 

 Chall. II, 1877. p. 226, woodcut, p. 224. 227. — Al. Agassiz rimll. Echin.. 

 1881. p. 45, Pl. II, lig. 2, 9, 10, 18. 



- Berlin. Mon. Ber., April 18(i8, p. 178. 



' Conipare the autlior's memoir on Pourtalesia, p. 20, 25, Pl. XIV. tig. Hm 

 — 171; woodcut, p. 26. 



♦ 1. c. fig. 163. 165. 167. 



•■• 1. c. fig. 164. 164 A, 166, 168. 



