GENERAL MORPHOLOGY, DISTRIBUTION, &C. Ech. 5 
Perrier & Poirier (33) are at issue with Ludwig with regard to the 
characters of the “heart,” and other parts of the vascular system, and 
they regard the former as merely a simple gland. . 
Jourdain (22) describes five ducts as forming the genital passages of 
Asterias , and thinks that, as in Holothurians, the products escape to the 
exterior by a pore in the circum-oral circlet, and not by interradial per- 
forated plates. Perrier & Poirier (34) find, however, in A. glacialis 
groups of small holes which are set a little above each interradial angle ; 
the circular dorsal canal has nothing to do with the generative system. 
Koehler (26) regards the Polian vesicle of regular Echinoids as an 
excretory organ; aud comes to the conclusion that the internal organs of 
the irregular have been, as compared with those of the regular Echinoids, 
profoundly modified. 
Danielssen & Koren (15) describe the madreporite of Trochostoma as 
being placed on, but not at the extremity of the sand-canal, while* in 
Kolga the canal retains the embryonic character of being open in the 
adult. 
Boll (10) takes Ophiomastix annulosa as a text for some observations 
on heteractinism, and objects to the use of term “voluntary” as applied 
to fission. He thinks that the origin of the habit of self-mutilation is to 
be found in the imperative necessity of reproducing the species, and was 
first used as the means for evacuating the genital products ; now it is 
true asexual reproduction. He gives the following table of the means of 
reproduction ; — 
a. Sexual reproduction. 
a. With metamorphosis. 
b. Without metamorphosis (viviparous forms). 
B. Asexual reproduction. 
a. Fission, with repair. 
b. External gemmation from a single arm. 
Bell (7) thinks that the presence of a variety of Antedon eschrichti in 
the Antarctic Regions brings forcibly forward the question of the so- 
called monophyletic or polyphyletic origin of species. 
Distribution, &c. 
Echinoderms of the Arctic Seas ; Hoffmann (21), Danielssen & Koren 
(16). 
Holothuroidea of the Arctic Seas; Danielssen & Koren (15). 
Echinoderm fauna of South Coast of New England ; Yerrill, Am. 
J. Sci. (3) xxiii. pp. 138-142, xxiv. pp. 362. And id. for Arctic Echiuo- 
derms, op. cit. xxiii. pp. 247 & 248. 
Echinodcrmata of Faroe Chauuel : Holothuroidea by H. Theel, P. R. S. 
Edin. xi. pp. 694-697; Echinoidea by A. Agassiz, pp. 697 & 698; Asteroidea 
by W. P. Sladen, pp. 698-707 ; Ophiuroidea , by T. Lyman, p. 707. 
Conoids of the Caribbean Sea ; Carpenter (12). 
Echinoderms of the Eastern Atlantic ; Greef (20). 
Echinoderms off the Coast of Brazil ; Ludwig (29). 
Echinoderms of Ceylon ; Bell (10). 
