ZOOLOGY AND BOTANY, MlCROSCOiPY, ETC. 575 



believes that " in the investigation of the spiuulation of star-fishes 

 there is a wide field for the study of those mechanical causes with 

 which the zoologist is concerned." 



Organization of Adult Comatulidae.*— E. Perrier finds in Antedon 

 rosaceus and A. phalangium that the "axial organ" is a tubular cavity 

 with glandular walls ; of its diverticula some appear in section to be 

 cffical, while others arc continued into canals, most of which pass 

 towards the dorsal integument and form around the oesophagus the 

 spont^y organ of H. Carpenter. The canals (the author cannot call 

 them°vessels) take a sinuous course, anastomose frequently, and have 

 walls which are clearly glandular ; they open by ciliated infundibula. 

 The author regards all these as parts of one and the same system, 

 and as comparable to the madreporic plate, sand-canal, and ovoid gland 

 of Echinids, Asterids, and Ophiurids. Perrier finds in the characters 

 of youn^^ larvre— such as the disposition and mode of formation of the 

 single canal— facts which lead him to think that the organization of 

 the°Comatulid is closely allied to that of other Echinoderms. Re- 

 serving details he here points out that if we consider an urchin as a 

 Orinoid whose arms have become firmly united with the disk (as is 

 the case, for example, in Eucalyptocrinus), and whose mouth was 

 situated at the point of insertion of the disk to the stalk, the nervous 

 system and the ambulacral canals of the urchin would have exactly 

 the same relations as those which are presented by the Comatulid. 

 He further remarks that the calyx of numerous Crinoids becomes 

 invaginated and presents points which are not without analogy to the 

 lantern of Aristotle in certain (and especially in Clypeastrid) Echinids. 



Ccelenterata. 



Anatomy of Campanularidae.t— It is generally believed that 

 the " theca " and the chitinous layer which covers the stem in the 

 Hydroida is a secretion from the ectoderm layer of the polyp. This 

 however docs not seem to be the case with the Campanularise. 

 H. Klaatch has been furnished by a detailed study of Chjtia johnstoni 

 with evidence tending to show that the chitinous sheath of the 

 Campanularia) is a product of differentiation of the ectoderm, an 

 epidermoid f(jrmation, the equivalent of a tissue. If this were not so, 

 and if the chitinous layer were a mere secretion from the ectoderm, as 

 it is in Cordylophora lacustris according to the researches of F. E. 

 Schultze, we should expect to find the whole of the body of the polyp 

 covered by a continuous layer of ectoderm entirely similar every- 

 where, and the growth of the chitinous covering to be increased by 

 the deposition of fresh layers of horny substance ; on the contrary, it 

 aprjears that the outer epithelium which covers the tentacles, the 

 head, and the " body " of the polyp is not continuous with that of 

 the stem, but at the posterior end of the stomach bends back and 

 becomcB continuous with the calyx itself, actually passing into it, the 



♦ Oirriptcn U. udiiH, xcviii. CIHRl) j)p. 1118-50. 

 t Morph. .Jtthrb., ix. (1884) pp. j31-'JG (3 i)la.)- 



