ON THE APPENDICES GENITALIS (CLASPERS) IN THE GREENLAND SHAKR. 



spine is still plainly felt in the somewhat smaller fins, excepting the two smallest; in these evidently 

 it has not vet been calcified, no more than most of the other parts of the skeleton, characterizing 

 the end or terminal part of the developed organ; therefore these small appendages are npon the 

 whole rather soft to the feeling and with flexible ends. 



The form of the developed appendage is straight, somewhat dorso-ventrally flattened ; a distinc- 

 tion may be made between the considerably longer proximal part, which might be called the shaft, 

 and the short distal part, the terminal part, which is free of the fin, and, as will be more parti- 

 cnlarlv bespoken hereafter, possesses a certain limited mobility; the largest breadth is found imme- 

 diately before the terminal part; on the dorsal side, somewhat nearer to the lateral than to the medial 

 edge, is seen the peculiar cleft, the appendix-slit, which is found in all Selachians; it reaches 

 to the posterior end of the member, and leads in the free part of this into a deep canal, more 

 anteriorlv into a glandular bag, which, like a deep pocket, at the base of the appendage goes round 

 to the ventral side of the fin, and here under the skin reaches — according to age and development — 

 a longer or shorter distance towards the pelvis. The inner walls of this bag are smooth, partly 

 pigmented, and from their epithelium is secreted a peculiar fluid, which when coagulated is tallowy, 

 but whose function is not certainly known. This bag, as to its origin, is simply a folding in of the 

 outer skin 1 ); it is surrounded with muscles, able to press the secretion into the canal and through 

 the slit to the exterior. The inner (medial) lip of the slit is immovable and cannot be displaced, 

 while the outer (lateral) one till near the terminal part consists of soft tissue, and is therefore easily 

 opened, so that a finger may be introduced into the bag; but at the end of the shaft, immediately 

 before the terminal part, all distension is prevented by the inner skeleton, which is found here, and 

 straightens the slit, so that it becomes very narrow; to the distal side of this straightening, in the 

 terminal part ifself, the canal may again be opened, and it will open spontaneously, if the terminal 

 part is bent a little in the ventro-medial direction, in which case the spine will at once erect. 



The following measures referring to the largest appendages, may be added: 



Length from the anterior border of the cloaca to the terminal point of the appendage 24 — 26 cm . 



of the terminal part of the appendage 5 — 5'5 cm . 



Breadth of the appendage before the terminal part 3'3 — 4 cm . 



Length of the slit i6 cm . 



of the part outside the fin 6 cm . 



Part outside of the point of the fin-membrane 5 c,n - 



The skeleton (pi. I, fig. 1—9). The skeleton of the ventral fin in the male consists of 1) the 

 pelvis, 2) the axial part or the stem, wdiich laterally wears 3) the rays, and as a continuation 

 4! the skeleton of the appendage. 



The structure of the pelvis is as commonly in the Sharks, it consisting of an unpaired, some- 

 what arcuated cartilage, the surface of which is rather slightly calcified ; it has the greatest thickness 



' I have followed its development in embryos of Acanlhias , as has also been done by Petri: Die Copulations- 

 organe der Plagiostomen. Zeitschr. f. -\viss. Zoologie, vol. 30, 1878. 







