4 PANAMIC DEEP SEA ECHINL 



at first closed by a single plate with additional plates formed along its 

 edge, — an embryonic condition which remains permanent in the Saleniae. 

 In the Arbaciadse there are four primordial anal plates, these vary in 

 number in the family, but are never as numerous as in the Echmidae, 



K~i^ jii 



1.5 mm. 

 Fig. 15. GONIOCIPABIS CAXALICrLAXA. 



Cidaridse or the majority of the genera of the order. In one of Loven's 

 figures (Echinologica, PI. IT. fig. 6) there seems to be an agglomeration 

 of plates, forming the dorso-central disk of Goniocidarw canaliculata ;^ a 



1 Dr. Mortensen (Ingolf Exped.) distinguishes Goniocidnris nutrix (PI. X. figs. 3, 4 ; 12, 14 ; 24) from 

 Gnnioci'laris canaliculatn (PI. VIII. figs. 6, 8, .32) by the pedicellariae. The figures he gives of the 

 large globiferous jiedicellaria; of G. itulrix differ from one another more than do the globiferous pedi- 

 cellariaj which he give.s as characteristic of each species. It is not inconceivable, as Dr. Mortensen 

 thinks, that the young .should be carried in a marsupium composed of either the actinal or abactinal 

 spines. The fact that Thomson describes the former method and I have figured the latter does not 

 imply any pre-eminent structural difference. Surely Dr. Mortensen does not pretend to imply that 

 the eggs or the young are hatched round the actinal surface, because at some time in their develop- 

 ment they have found their way there. That they are retained in a marsupium of the spines either 

 of tlie aotinal or abactinal areas does not seem to be an important pliysiological character; it may 

 depend upon local conditions tending to the greater or less growth of the spines of either area. 



Dr. Mortensen refers (L cnnalieuUita to SUreocuUnis, though Doederlein thinks they are more 

 closely related to Dnmciilnris. I can hardly think it advisable to refer such a variable species to 

 either of these genera, though, .-is I have stated in my '• Challenger " Rejx)rt, the characteristic Gotiio- 

 cidaris features are frequently greatly obliterated. The great bathymetrical range of the species, as I 

 understand it, is not, a.s Dr. Mortensen imagines, prima facie evidence that the very variable speci- 

 mens found at tlie extremes of the range must belong to different .species. Surely the bathymetrical 

 lists I have given in the " Challenger '' and " lUake " reports sliow a number of cases in which the 

 range is fully an great as the objectionable range of this sjx'cies. I have on sever.al occasions called 

 attention to the great bathymetrical range of many species of Echini, and it is not nece.ssary to call 

 attention to it every time they are mentioned. Dr. Mortensen will find on pp. 46 and 209 of the 

 "Challenger" Echini a list of the localities at winch I stated O. canaliculatn to occur, — stations 

 ranging in depth from 5 to 1975 fathoms. I may be mistaken in referring all these specimens to 

 G. ranaliculata, but their range is indicated, and I have not suppressed it, as is stated by Dr. 

 Mortensen. 



