OX THE APPENDICES GENITALIAS iCI.ASPERS) IN THE SELACHIANS. 



45 



The peculiar mixture of Shark-like and Ray-like characters that, as it is well known, is found 

 in RAina, is accordingly increased by several features in the appendages of the male, which features 

 by the ventral covering piece and the pocket, situated below it, with entrance from a side-slit, and 

 partly also by the glandular bag, recall those in the Rays (Torpedo, Narcine, Rliiiwbatns and Trygon\ 

 while most of the other features are those common in other Sharks. 



Cestraciontidce. 



Heterodontus (Cestracion) Phillipi (Cuv.). 



The skeleton has been described by Gegenbaur 1 ;. Between the basale and the appen- 

 dix are found two pieces (b t , b 2 = /?, /?', I.e. fig. 18, io| that bear no 

 rays; the piece fj is well developed (1. c. b fig. 19). The chief piece of 

 the appendix is provided with two (rather long?) marginal cartilages (the 

 boundary lines of which cannot be seen in the figures of Gegenbaur, 

 as he has not understood the marginal cartilages to be particular pieces), 

 of which the ventral one has a dorsally bent plate (I.e. fig. 19, a); the 

 stem is prolonged into a long style reaching almost to the end of the ter- 

 minal part (1. c. fig. 19, 20, / ). The number of terminal pieces is four: Td 

 {^=\. c. fig. 19, 20, 0), Td 2 (= 1. c. u), which, as is often the case, is prox- 

 imally prolonged into the appendix-slit; Tv (= I.e. c) , as commonly, 

 stronger and thicker than the others, and finally T, forming a short thorn. 

 Gegenbaur has correctly seen the homologies of these pieces with those 

 in Acanthias , where , however , he has not seen the piece Td 2 (= u in 

 Heterodontus). Of these terminal pieces the piece T, is said (1. c. S. 452) 

 to be hard, while the others, though fully developed, are still cartilaginous. 



RJ 



Rv(a) 



(<*>Z~ 



(u)Tdi 



Td 



(»J 



-R11 



ill 



-Tv 



-Tvle) 



(o)rd--M : 



Fig. 15. Heterodontus 

 Phillipi. The skeleton 

 of the right appendage. 

 After Gegenbaurfl.c. 

 fig. 19I. somewhat re- 

 duced. The letters pla- 

 ced in parentheses are 

 those used bvGegen- 

 baur. r the last rav. 



Notidanidce. 2 ) 



Chlamydoselachus anguineus Garman. 



Fig. 16. Chlamydo- 

 selachus anguineus. 

 The skeleton of the 

 right appendage. 

 After Gun ther, 

 somewhat reduced. 

 The letters in the 

 rudimentary and one larger intermediate cartilages" {b T , b 2 , b 3 , b 4 i) , none parentheses are the 



of which bears any ray. To judge by the figure , there is no piece 8 ; original ones. 



Giintherj) has briefly described the appendages and their skeleton, 

 and given figures of them. Only a third part of the length of the appen- 

 dages is free of the fin, a as is the case in the Notidanidce generally", and 

 there is no notch in the hindmost fin-edge, between the membrane and 

 the appendage. Between the basale and the appendix-stem there are « three 



along the ventral marginal cartilage to the lateral surface of the appendix-stem, we should have a similar state of matters as 

 in Khina. There can scarcely be any doubt that the gland in this Shark and in the Rays — in spite of the difference of po- 

 sition — are in realitj- homologous. Furthermore the glandular bag in younger stages of the Rays seems to pass through a 

 stage of development, in which there is, also as to the exterior, a conspicuous similarity with that of the Rhiua, without any 

 conspicuous longitudinal furrow etc. (see later under Raja iatis). 



'1 Ober die Modificationen etc. 1S70, p. 450, Taf. XVI, fig. 18—20. 



2 1 I regret very much that my efforts to get ventral fins with developed appendages of Hexanchus or Heptanchus 

 have been in vain. The figure of the skeleton of Heptanchus ciuereus Ag. given by Fritsch in Fauna der Gaskohle etc. 

 Bohmens, vol.3, 1895, p. 43 is quite useless. From this figure appears only that at least the two terminal pieces Td and Tv 

 are found; what Fritsch calls the sporn is the last ray (or rather the two last, coalesced ones). The 1 of the figure, I 

 suppose to be the piece /J, and it is certainly not the - Letztes Glied des Hauptstrahles ■. The figures of the structure of the 

 appendages in the extinct Xenacanthida: , given by Fritsch as well in his chief work as in several articles in the Zool. An- 

 zeigers 18S8— 91, I think to be justified in designating as unreliable; but by means of the published figures alone the real 

 structure cannot be determined. 



1 Voyage of H. M. S. Challenger, Zool., Vol. XXII, 1SS7, S. 2, Tab. LXIV, fig. C,D,H. 



