on THE APPENDICES GENITALES (CLASPERS) IN THE GREENLAND SHARK. I( 



to the naked eve the section shows a particular fibrous texture (as in sections of the terminal pieces), 

 and a whitish colour, distinguishing it distinctly from a section of the appendix-stem or any other 

 part of the skeleton proper, for inst. a ray or the basale, the surface of which will be hyaline. From 

 these developmental facts it will appear with all desirable distinctness, that the marginal carti- 

 lages and the terminal pieces are secondary parts of the skeleton, developed in the 

 tissues surrounding the primary skeleton, properly so called. Tims of the appendix-skeleton only 

 the appendix-stem, the piece b, belongs to the primary skeleton. 



To resume what is said about the appendix-skeleton in the Greenland Shark: 



The appendix-skeleton consists of a chief piece and terminal pieces movably connected with 

 it; the chief piece is formed by the coalescing of the appendix-stem with two secondary calcified 

 cartilages, the marginal cartilages; the appendix-stem belongs to the primordial axial skeleton of 

 the ventral fin, being the terminal joint the extremity of which remains soft; the terminal pieces 

 are all secondary calcified cartilages. 



The muscular system (pi. V, fig. 58 to 62) follows the type, which has been described in 

 Acanthias by v. Davidoff 1 ); this type, however, has been founded on the structure of the ventrals of 

 the female; the rather considerable differences from it are due to the copulatory appendages, for 

 the special use of which special muscles have to be developed. Distinction may be made between: 

 I) The fin muscles proper, and II) the muscles of the appendage; as, however, some of the former 

 spread over part of the appendage, this distinction cannot be made quite distinct. 



I. In the fin -muscles proper may be distinguished, as v. Davidoff and the earlier 

 arithors do, between the muscles of the ventral and those of the dorsal side; they are anta- 

 gonistic, the former adducting the fin, and removing it from the abdomen, the latter abducting the 

 fin, and pressing it against the abdomen. 



1) The ventral muscles of the fin consist of a) a medial muscular mass, chiefly reaching 

 from the pelvis to the stem-skeleton of the ventral, with laterally and obliquely -posteriorly directed 

 bundles of fibres, and b) a lateral mass, the muscles of the rays, issuing from the stem-skeleton, and 

 following the rays to the fin-membrane. 



a) This powerful groirp of muscles (pi. V, fig. 58 — 61, A and E) in so far does not wholly be- 

 long to the ventral side, as, besides forming the medial edge of the fin, it is also seen on the dorsal 

 side. Looking first at its ventral side we find its origin covering almost the whole ventral surface 

 of the pelvis: between the fin-muscles of the two sides only a triangular piece of the pelvis is to be 

 seen in the middle anteriorly, from the top of which a narrow uncovered streak runs backward to 

 the end of the above (p. 8) described process; from this issues further backward in the linea alba 

 an aponeurotic streak (fig. 58, s), which continues the pelvis, and serves as attachment for part of the 

 same muscular mass. The superficial ventral part is for the greater part composed of distinct bundles 

 of muscles, enveloped in rather firm sheaths of connective tissue, and mostly corresponding in number 

 and direction with the muscles of the rays; but this composition of isolated bundles is effaced anteriorly- 

 laterally and posteriorly-medially. 



Anteriorly the fibres running obliquely from the pelvis towards the outer margin of the fin 



■i Beitrage zur vergleichenden Anatotnie der hinteren Gliedmasse der Fische. Morphol. Jahrbuch. 5 Bd., 1S79, p. 454 seq. 



2* 



