12 ON THE APPENDICES GENITALES (CLASPERS) IN THE GREENLAND SHARK. 



form a rather solid mass spreading from the fore edge of the pelvis over the broad ray R. The fore- 

 most of the following distinct bundles of muscles cross the ventral surface of the basale reaching as far 

 as to the horny filaments^ of the fin-membrane, ending here in a tendinous mass; the following bundles 

 only reach to the basale where they are inserted with tendinous ends, from which tendinous part the ray- 

 muscles originate as a prolongation — however, when we look farther backwards, with a distinct inter- 

 position of a narrow stripe of the basale. Between the said foremost bundles, continuing immediately in 

 the ray-muscles, and those attached to the basale, a gradual transition is found, a tendinous part in 

 the superficial layer of the bundles being inserted on the place of transition. 



The hindmost and medial part of the muscle A is not composed of isolated bundles, but its 

 fibres running rather straightly backwards form a solid mass, inserted on the distal end of the basale, 

 on the pieces 6^, and 62, and on the proximal end of the chief piece of the appendage [d). 



The whole muscular mass, as mentioned, is of a considerable thickness; its deeper part which 

 is also seen from the dorsal side, is not divided into separate bundles; this deeper, more dorsal, part 

 originates from the rounded posterior surface of the pelvis, and even reaches to its dorsal surface; it 

 is inserted along the medial side of the basale and the following joints in.side the insertion of the 

 described superficial \'entral layer. 



With this muscle A is closely connected another (pi. V, fig. 59 and 61, £), chiefly seen from 

 the dorsal side. It originates on the medial side of the basale, a little before the middle, its fibres 

 crossing those of the muscle A, and spreading over the appendage; as above the knee of the latter 

 the fibres run obliquely across the medial edge of the fin and on to the ventral side, part of the edge of 

 this muscle will consequently be discernible on this side (pi. V, fig. 58 and 60 ^E). It is spread like a 

 cloak over the chief muscle (D) of the appendage forming a rather thin plate and growing thinner from 

 the ventro-medial edge laterally (c^x fig. i in the text); its fibres are attached, parth' along the narrow 

 ridge, formed by the dorsal marginal cartilage along the ajjpendix-slit (fig. 61 /i/) parth-, distal!}-, to a 

 thin, firm aponeurosis {iig.Gia], covering the muscle D, and attached to the elevated distal part of 

 the dorsal marginal cartilage {R(/}. In somewhat older animals with well developed appendages this 

 muscle £ is as well proximally as distally distinct!}- separate; in \-oung animals, however, with 

 only little developed appendices (fig. 59) the distal part is still very distinctly marked, but the proximal 

 part is less sharply separated from the large muscular mass A ; numerous bundles coming from the 

 pelvis and the aponeurotic streak J unite with those from the basale, and numerous bundles from the 

 basale run over among the former and reach to the proximal end of the appendix-stem. 



The above described muscular group consisting of the muscles A and £, will, according to 

 circvnnstances, be able to act in two different ways; these muscles will, when the antagonists of the 

 dorsal side are not contracted, move the fin from the abdomen, and at the same time draw its inner 

 edge towards the median line, thus moving the two fins towards each other; and when the dorsal 

 antagonists act on the fin, they will move the appendix only, towards the median line, tlius 

 acting as extensors for the appendix; the latter action will be facilitated by the nuiscle £ acting 

 rather distally on the appendix (an effect as to the opening of the appendix-slit is of course out of 



