ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 443 



near the disc, or at a variable distance along the ray ; the pyloric caeca 

 are always pnlled out and much stretched ; the break of the caecum 

 occurs at the tube connecting the stomach and glandular portion ; the 

 pyloric caecum is generally taken back into the arm ; the severed ray 

 may live more than a week without signs of regeneration ; rays cut 

 at various distances from the disc make discs, mouths and new rays in 

 about six months. 



Sea-urchins of German Deep-Sea Expedition.* — L. Doderlein 

 describes fifteen forms, all of which, excepting one, are new species, 

 and amongst which are representatives of five new genera. 



The Origin of the Water- Vascular System of Echinoderms.f — 

 E. Meyer seeks to throw some light on this question. He homologises 

 the two ccelome divisions in the Prosopygia with the two pairs of ccelome 

 vesicles of the echinoderm Dipleurula larva. These cavities are not to 

 be regarded as ccelome metameres. They are comparable in origin, rather 

 to the anterior and posterior thoracic cavity of Terebellids, through the 

 disappearance of regular intersegmental septa, and equivalent to the sum 

 of several segment cavities. The hydrocoelic vesicles of echinoderm 

 larvae, on the contrary, have, since they correspond to the diaphragm 

 sacs of Terebellids, merely the significance of a muscular hollowing out 

 of a dissepiment which has remained between the anterior and posterior 

 ccelome. The ontogeny of echinoderms bears this out, since both hydro- 

 ccels, rudimentary and definitive, arise typically as eversions of the 

 hinder epithelial wall of the anterior ccelome. The evolution of the 

 complex hydraulic apparatus of the adult echinoderm from such open 

 diaphragm sacs, is partly to be understood by reference to certain Anne- 

 lids, for example, Saccocirrus, in which in the head and tentacles there 

 exists a canal- and ampullae-system comparable to the echinoderm water- 

 vascular system. 



South African Echinoderms.J — F. Jeffrey Bell reports on Asteroidea 

 and Ophiuroidea found off the coast of South Africa. The Cape Star- 

 fishes show an alliance with those of the North Atlantic, but there are 

 also indications of the presence of species best known as yet from the 

 Indian Ocean ; this is, indeed, only to be expected when we examine the 

 trend of the currents round the southern peninsula of the Old World. 

 A new Pahnipes (P. novemradiatus) is described, the only one known 

 with more than five rays, and the total list mounts up to a score. The 

 author notes the variability of Astropecten pontopormus, and the growth- 

 stages of the previously rare and little known Pentagonaster tuberculatus 

 of Gray. 



The Ophiuroids number eleven, including Ophiozona capensis sp. n., 

 and Ophiura trime/ri sp. n., and a good series of the hitherto rare 

 Ophiothamnvs remotus, which was dredged by the 'Challenger' in the 

 neighbourhood of the Cape. Professor Bell notes that the study of 

 Ophiuroids has suffered much from the description of isolated " species " 

 based on one or a few specimens. This is notably the case with Ophio- 



* Zool. Anzeig., xxviii. (1905) pp. 621-4. 



t Zool. Jahrb., xxi. (1904) pp. 339-78. 



I Marine Investigations in South Africa, iii. (1905) pp. 241-53, 255-60 (1 pi.). 



