484 THE ANATOMY OF INVERTEBRATED AXIMALS. 



ambulacral vessel, but is also covered by the superambulacral 

 plate. A neural canal lies between the nerves and the ambu- 

 lacral vessels. The pedicels are tentaculiform, and have no 

 vesicles at tlieir bases. The genital glands are lodged in the 

 disk, and pour their products into the peritoneal cavity, which 

 communicates freely with the exterior by vertically-elongated 

 apertures placed interradially on its margins.* According to 

 Metschnikoff, Ophiolepis squamata is hermaphrodite. 



The early conditions of the embryos of most Ophinridea 

 are similar to those of other Echinoderms, and acquire the 

 characteristic bilateral ciliated zone ; but in some the embryo 

 does not become an Echinop)oedm'm^ but passes directly into 

 the adult condition. Thus Krohn discovered that the embryo of 

 Ophiolepis ciliata is developed within the body-cavity of the 

 parent, to which it adheres by a kind of pedicel. "Where an 

 Echinopc^dium stage exists, the larva is a Fluteiis (Fig. 135, 

 C C). The dorsal wall of the body of the embryo exhibits a 



Fig. 140. — A, OpMoIejns ciliata, oral skeleton from within (after Miiller) : a, dor- 

 sal marjrinal plates ; b. ventral plates ; rf, vertebral osfeicles ; e, interambulacral 

 pieces of oral angle ; /, torne annularis ; q, apermrep for oral tentacles ; h, posi- 

 tion of nervous collar ; i, impression of circular ambulacral vessel ; k, orifice in 

 the first ambulacral plate for the tentacular branch of the oral vessel ; o, palse angu- 

 lares. B, Adrophyton, onil skeleton seen from within (.after Muller): m »2,peris- 

 tomial plates ; other letters as in A. 



median conical outofrowth : along: the course of the ciliated 

 band symmetrically-disposed processes are developed ; and 



1 Miiller, " Ueber den Bau der Ecbinodermen " ("Abh. Berl, Akad.y 

 1853) ; Teupcher (I. r.) ; Simrock, " Anatomic und Schizogonie der OpJiiaetis 

 mrens^^ (Zeitschriftfur wiss. Zootogie^ 1876). The latter writer describes nu- 

 merous apparently coecal diverticula of the circular ambulacral canal, and of the 

 necks of the Polian vesicles {vasa amhiclacralia cavi) which traverse the peri- 

 toneal cavity in all directions. 



