ON THE APPENDICES GENITALES (CLASPERS) IX THE SELACHIANS. 



mal origin accordingly is much more backward, at the- distal end of the .1/. adductor; it is inserted 

 usual, its aponeurosis being especially attached to 7'r : and Td; the latter piece, the In. ok , is turn 

 (round its medial edge as the axis) out of its position in the spoon-shaped end of the former, when 

 the muscle is contracted during the dilation. 



The part of the M. compressor wrapping the bag, is much distended, and consequently rather thin, 

 corresponding to the considerable extent of the bay anteriorly (see fig. 4 in the text). The part inserted 

 on the lateral surface of the appendix-stem, is very small, reduced to a tew bundles of fibres on the 

 proximal end of this part of the skeleton, which otherwise is almost quite enclosed l>v the M. dilata 

 The part, which as outer lip-muscle forms the lateral limit of the appendix-slit, seems to me to 

 receive in its surface some fibres coming from the muscular layer originating from the lateral muscles 

 of the bod}', but otherwise it originates as usual on the hindmost ravs and on 8; it is inserted with 

 a kind of tendon in the above-mentioned membrane on Tv , and consequently it acts antagonistically 

 against the J/, dilatator, and at the same time lays the spur 7\ '). 



Spinax niger Bonap. 



iPl. I. fig. 12, 13.I 



The very peculiar-looking appendages in this common Shark have singularly enough been 

 very little mentioned by earlier authors, and by many, also among the later, they are not mentioned 

 at all. Gunnerus 2 ), in his description of the Sort-Haa , says: they (i.e. the two Membra genitalia) 

 were supplied with some sharp bony spines, such as I have seen on the Membra of several Rays, 

 when the ends have been turned inside out. Kroyer ; ) says: At the end of the copulatory appen- 

 dages of the males are found three crooked thorns or horny claws, and a tapering dermal flap, which 

 behind projects a little over these claws. The claws are movable against each other, and form a kind 

 of prehensile organ. In the position of rest they are hidden between a pair of small cartilaginous 

 plates, and the skin covering these plates. This is the most complete, and also, I think, the m 

 correct description I have seen*). DumerilM gives a drawing of the appendix, but with no explana- 

 tion whatever (nor in the text neither): the drawing is rather difficult to understand, neither is it 

 correct; tints the dermal flap mentioned by Kroyer appears in this figure as a thorn, although it is 



■i Petri (I.e.) designates this part of my M. compressor as M levator (fig. 5, >■'/). and attributes t" it a dil 

 effect, having allein die Aufgabe diesen (den Sporn) zu heben», and thus he in this place speaks .if two dilating muscles. 

 The incorrectness of this, however, is easily pointed out. Contrary to Petri, Bloch upon the whole 1m-. a correct understanding 

 of the mobility of the spur, speaking (I.e. p. 131 of einen sehr sonderbaren Mechanistnus. Davon mil wenigstens it 

 Anatomie kein ahnlicher bekandt ist . Bloch has a chiefly correct description of the muscular system; he distinguishes bet' 

 three muscular portions, the first of which being the ventral ray-muscles, the second, which he compares t" the add . 

 femoris in man, is my .1/ adductor, the third M. dilatator -f- my M. extensor. He describes the glandular ba 

 eular organ, to which lie docs not ascribe any muscular walls, as he supposes that the othei (2) muscles expel its 

 Feuchtigkeit . Neither has I'etri seen my M. extensor as a separate muscle in Acanihias (see his fig 

 tion ]). 5021; lmt it is also to be acknowledged that in this species it is very closelj connected with tin 1/ 

 proximally. 



z ) Throndhjemske Selskabs Skrifter II. 176;,. p. 319 



I) l>anmarks Fiske vol. Ill, 1852—53, p. 90S. 



;i Mfiller & Henlc, System. Beschr. der Plagiostomen, [841, p. 86, sa\ : Kein Dorn an den mannlicheii \: 

 founded, I suppose, on young specimens, in which onlj the soli dermal flap is seen. 



: l Hist. nat. des I'oissons. vol. I, [865, the atlas, pi. IV, fig. 13. 



