Bibliographical Notices. 351 



round the dorsocentral plate, ultimately leave that position, pass 

 on to the actinal surface, and become the so-called " odontophores ;" 

 (2) that the Crinoid calyx finds its homologies in the Echinoids in 

 the " lantern of Aristotle " and not in the plates of the apical 

 system ; and consequently that the mouth of an Urchin occupies the 

 position of the point of attachment between the stem and the body 

 of a Crinoid ; and, further, that the abactinal surface of a Starfish 

 corresponds to the actinal or buccal region of an Urchin and not to its 

 abactinal or apical region. Dr. Herbert Carpenter points out that the 

 former of these views had been refuted previously, on grounds which 

 he considers to be cogent and logical, and to which M. Perrier 

 makes no reply in his recent work, wherein the same views are again 

 advanced. The homologies which M. Perrier seeks to establish in 

 the case of the Echinoids and Asterids are shown, both on morpho- 

 logical and rational grounds, to be altogether untenable. We also 

 notice that the author does not accept M. Perrier's assumption that 

 the " dorsal appendage " of Caulaster is homologous with the stem 

 of a Crinoid ; or the similar views of Drs. Dauielssen and Koren in 

 the case of their genus Ilyaster. It is pointed out that the former 

 of these Asterids has been considered to be only the young of Por- 

 cellanaster, and that M. Perrier's comparison of the plates round the 

 dorsal appendage of Caulaster with those forming the periproct of 

 an Urchin cannot be followed out in detail. 



In three succeeding " Notes " certain statements of M. Perrier 

 on the anatomical structure of Comatula are criticized. (1) His 

 assertions that the water-tubes depending from the oral ring are in 

 direct continuity with the inner ends of the water-pores of the disk, 

 that some of the water-pores open into the glandular tubules of the 

 labial plexus, and that the canals forming the inner ends of the water- 

 pores on the lower part of the disk open into the cavities of the cham- 

 bered organ, are regarded by the author as highly improbable, not 

 only on structural grounds, but because it is hardly possible to ima- 

 gine that these connexions could have remained unobserved by the 

 numerous competent investigators who have recently studied this 

 form with the greatest care. (2) The canals regarded by Prof. 

 Ludwig and Dr. Herbert Carpenter as intervisceral blood-vessels 

 are believed by M. Perrier to be merely parts of a vast aquiferous 

 system. The improbability of this assumption is shown from the 

 fact, that the body-cavity through which they ramify already con- 

 tains water, admitted through the water-pores ; that their lumen is 

 frequently filled up with coagulum ; and that it would be hard to 

 understand the object of a special set of aquiferous tubes distributed 

 over the coils of the digestive canal and not communicating with the 

 ambulacral system, but with the axial organ and the labial plexus. 

 M. Perrier's theory of the fundamental unity of the water- and 

 blood-vascular systems of Echinoderms is regarded as untenable, 

 and unworthy of recognition until a basis of definite proof is esta- 

 blished by figures and facts, instead of the mere assertion upon which 

 the assumption at present rests. 



The concluding " Note " in the Appendix is devoted to the nervous 



