75 i SUMMARY OF CURRENT RESEARCHES RELATING TO 



alone among the neonomous Echinoids in having homoiopodous 

 pedicels, none of which are disciferous or converted into respiratory 

 leaflets. The spines are Spatangean in characters. They do not 

 attain to the level of the Spatangidse owing to the frequent loss of the 

 organ of vision as well as by the simplicity of their pedicels. By 

 some of their characters they point, though remotely, towards animals 

 of another and higher type, animals of annulose differentiation. 

 They are found in all oceans, and, on the average, at a depth of 

 2900 metres. 



As to the origin of the deep-sea fauna Prof. Loven utters these 

 pregnant sentences : " In the adult state most of the marine Evertebrates 

 remain at their native station, wandering within its precincts. Their 

 embryonic and larval age is their period of dispersal. Of numerous 

 littoral forms, of different classes, tribes, and orders, currents must 

 occasionally carry away the free-swimming larvas .... far into the 

 sea, and during the course of succeeding generations early stages of 

 many a species will in this way have reached the wide ocean. There 

 they will have sunk, their development accomplished all through 

 depths full of danger and more and more uncongenial, and a few of 

 them will have settled on the bottom of the abyss, and fewer still will 

 have come to thrive there. Among these some will long have their 

 original character, and but slowly been modified, while others 

 will have exhibited a latitude of variation unknown or rarely seen 

 where they came from, but upon the whole there will be reasons for 

 assuming the less altered forms to be new comers, the more deviating 

 to be old inhabitants of the deep." 



Anatomy of Larval Comatulse.* — Dr. P. Herbert Carpenter 

 closely criticizes some of the results lately published by Perrier."!" 

 He expresses his doubts as to the single curved water-tube of the 

 " cystid-phase " opening to the exterior by a pore on the wall of the 

 body, and inclines rather to Lud wig's exact account of the primary 

 water-tube as a dependence of the water-vascular ring opening into 

 a section of the body-cavity, into which the primary water-pore, 

 which pierces the oral plate, also opens. He doubts also the 

 continuity of the pore and tube in later stages of the larva. 



" The most startling statement " on the part of Perrier is that the 

 plexiform gland of Crinoids corresponds, not with the ovoid gland of 

 Star-fishes and Urchins, but with the stone-canal of these echinoderms. 

 The ground for this statement can hardly be histological, and it is 

 difficult to imagine what it may be. The relations of the axial organ 

 to the cirri can hardly be seriously maintained, unless Perrier will 

 show that the cirrus-vessels are radial and derived from the cavities 

 of the chambered, organ. Dr. Carpenter reiterates the expression of 

 his hope that Perrier will publish more complete accounts and 

 illustrate them by a number of figures. 



* Quart. Journ. Micr. Sci., xxiv. (1884) pp. 319-27. 

 t See this Journal, ante, p. 389. 



