136 CLASS IV. 



remarkable. Amongst the Ophiurce, Ophiolepis squamata is vivi- 

 parous. The young, about ten in number, are developed between 

 the integument and the wall of the stomach of the parent, in the 

 inter-radial spaces, each in its own compartment, formed by mem- 

 brane extended between the wall of the body and the stomach and 

 suspended by a ligament attached near one of the angles of its disc. 

 When fully formed it passes out by one of the genital fissures 1 .] 

 In Eckinaster sanguinolentus the embryo according to the observa- 

 tions of SARS 2 , on its escape from the egg is of an oval form and 

 covered with cilia. Presently excrescences, club-shaped processes, 

 arise at one extremity by which it adheres to the inferior surface of 

 the disc of its parent, now converted by the infolding of the rays 

 into a brooding cavity. When the arms begin to shoot forth these 

 processes disappear, and feet or tentacles, few in number but pro- 

 portionally very long, serve for the creeping and adhesion of the 

 creature. The whole development occupies six or seven weeks. 

 When the clavate processes are about to disappear they are near the 

 edge of one of the inter-radial spaces of the disc of the Echinoderm. 

 Of CamatulcB it had been discovered by THOMPSON 3 that during an 

 early period of their life they are fixed to a stem and then resemble 

 Pentaerini, in other words, that the form which in Pentacrini is 

 permanent, is in them transitory. But their previous metamorphoses 

 were unknown. [BusCH has observed these changes from the egg 

 until the period when the embryo is about to be attached. The egg 

 having passed from the parent by an aperture at the side of the 

 pinnulce, remains attached to the pinnula by an abundant mucus, 

 from spherical becoming oval, and the embryo may be seen rotating 

 within the egg by means of its general covering of cilia. When the 

 egg falls from the pinnula the embryo escapes : its oval form is 

 elongated, the straight sides assume a gently undulating contour : on 

 the tops of the undulations transverse bands of larger cilia are seen 

 in place of the general ciliated covering : the bands are at first three 

 in number, afterwards four, surrounding the body in parallel circles : 

 the longitudinal axis of the body now becomes gently curved, and a 

 mouth is seen on the concave surface : the bands of cilia disappear 



1 KROHN in MUELLER'S Archiv. 1851, s. 338 343. 



2 SARS in WJEGMANN'S Archiv. x. s. 169. 



3 THOMPSON, Edinb. New Philos. Journal, xx. p. 295. 



