ZOOLOGY 70? 



V. — ECHINODERMS. 



Crinoids. 



Basal plates of Crinoids. — It has been asserted that some Crinoids- • 

 for example, those of the family Engeniacrinidae — were destitute of basal 

 plates. Mr. P. H. Carpenter investigated representatives of the family 

 named, and was convinced that "the supposed absence of basals in cer- 

 tain Crinoids mostly rests upon empirical reasoning alone; and that 

 when we come to inquire into the matter rationally, i. e., from the point 

 of view of morphology, we not only find good reason to believe in the 

 existence of those plates, but also that their supposed absence involves 

 considerable morphological difficulties." {Ann. and Mag. Nat. Hist. (5), 

 vol. xi, pp. 327-334.) 



New orders of Crinoids. — Mr. S. A. Miller, in the second edition of his 

 American Palaeozoic Fossils, has proposed to isolate several of the family 

 types of Crinoids as distinct orders. The Agelacriuidae have further the 

 name Agelacrinoidea, the Liehenocrinidae constitute the order Licheno- 

 crinoidea, aud the ordinal name Myelodactyloidea is intended for a group 

 of two families — the Myelodactylidae and Cycloeystoidae. The charac- 

 ters given to these groups appear to be scarcely those requiring recogni- 

 tion as orders. 



Asteroids. 



Number of Ophinroids. — In connection with a "Report on the scientific 

 results of the voyage of H. M. S. Challenger " (Zoology, vol. V, part 14), 

 the Hon. Theodore Lyman has attempted to enumerate all the species 

 of the order described up to the time of publication. Not less than 167 

 new species and 20 new genera were found in the collections made by 

 the famous expedition. 



Echinoids. 



Physiology of the Echinoids. — If a sea-urchin or Echinus is turned 

 mouth upwards it will commence to right itself, and does so by usiug 

 two or more adjacent rows of pedicels. Whether the consequent en- 

 deavor was due to the co-ordinating influence of a nerve center, or 

 whether it was the result merely of the serial action of the pedicels, was 

 uncertain, although various experiments tended to show that the action 

 must be due in part at least to the co-ordinating influence of a nerve 

 center. Mr. Romanes considers that he has now settled the question 

 by a device suggested by Mr. F. Darwin. 



A sea-urchin was placed back downward in a bottle filled to the brim 

 with water and then corked up. The whole was then placed on the 

 rotating apparatus used by the Darwins in their experiments on the 

 geometrism of plants, aud the sea-urchin was continuously rotated in a 

 vertical plane. While rotation was continued the sea-urchin made no 



