ON THE APPENDICES GENITALES (CLASPERS) IN THE SEI.ACHIANS. 17 



secretion, I design it — including the described outer lip-muscle of the appendix-slit — as Mitsculus 

 compressor (sacci). 



II. 



The Ventral Appendages in other Selachians. 



For comparison with the facts found in the Greenland Shark, I have examined as man>- other 

 forms of Selachians, as I have been able to get the material for, being soon convinced that the repre- 

 sentations, hitherto found in the literature, gave only a rather incomplete insight into the structure of 

 these organs, and only to a small degree were to be used comparatively. 



The greater part of my material has consisted of well preserved ventrals, a less part only of 

 skeleton parts, dried or preserved in spirit, which the director of the collection of Vertebrata of the 

 Zoological Miiseum, Professor Liitken, has been kind enough to place at my disposal. The following 

 description has been divided into three parts of very different extent, of which the first will give a 

 short general account of the copulatory appendages in the Selachians in general, the second a more 

 particular description of the forms, on which this general account has been based, and the third will 

 as a conclusion contain some short remarks as to what for the present may be regarded as tolerably 

 certain concerning the function of these organs. That the particular description will treat more of 

 the skeleton and less of the muscles is occasioned b)- the relatively .small variation of the latter. 



N 



I. A General View of the Copulatory Appendages in the Selachians. 



As to the outer form, the same outline is found in the copulatory appendages of all vSe- 

 lachians: it is always the inner part of the fin which is prolonged, and formed into an appendage, 

 and this appendage may be more or less free of the fin-membrane; it is most separated in the Holo- 

 cephales, least so in some Sharks; it always consists of a, longer or shorter, proximal part, the shaft, 

 and a, generally shorter, distal part, the terminal part, this latter being always free of the fin- 

 membrane, and (at all events in the Plagiostomes) possessed of a certain mobility. 



On the dorsal side of the appendage, sometimes, however, quite laterally, a deep furrow or 

 slit, the appendix-slit runs longitudinally, to the posterior end; the edges or lips of this slit can 

 always be opened, at least in two places, viz. at the foremost beginning of the slit in the shaft, and 

 behind in the terminal part; frequenth- the slit can be widened in a considerable part of the shaft 

 (Soiii)iwsiis, Acanthias. Spinax, a. o.); there is, however, always a part of the slit, in which widening 

 is prevented by the inner skeleton, or where the lips cannot at all be separated, or sometimes even 

 may be coalesced (the latter in Scylliuvi and Pristhtrns)\ the part of the slit situated in the terminal 

 part can (at all events in all Plagiostomes) be widened by muscular action, and again narrowed by 

 elastic reaction, sometimes as,sisted by muscular action. The appendix-slit is the duct of a glandular 

 bag which is surrounded by muscles, and in all Plagiostomes with its greater part situated on 



The Ingolf-Expedition. II, 2, ^ 



