ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 41 



is claw-shaped and of a considerable size (in the specimen before me 16"^'" long, and the broadest part 

 5,6"^" broad); with the exception of the proximal part it is completely calcified; according to the state- 

 ment of several anthors') the point of it (in the developed organ) projects throngh the skin. 



Besides the three terminal pieces seen in my figures, I think it probable that one more has 

 been found, a Td, as in Lainiin. I foiind this opinion in the first jjlace on the words of Blainville 

 (I.e. p. 126) that besides the claw there is im autre cartilage, un pen aplati, occupant le milieu du 

 tiers anterieur de cette gouttiere (i.e. the furrow of the terminal part); celui-ci etoit mobile presqu'en 

 tous sens, mais entierement renferme dans un repli de la membrane interne qui se prolongeoit, libre 

 et flottante, jusqu'a I'extremite posterieure du sillon . Next I found the above stated opinion on the 

 description (1878, p. 352) and drawing in woodcut (fig. 3) of the (undeveloped) appendix given by 

 Pavesi: vuella meta apicale offrono un pezzo mediano lanceolate, rialzato e piano, con fendittire laterali. 

 Questo superficie non ha traccia di sperone corneo... Later (p. 405) it is said of this piece that it is 

 only a thickened dermal fold, not to be confounded with the spur*-). The dermal fold mentioned 

 bv these authors, no doubt corresponds with that one which in Laii/iia contains the piece Td2^. But 

 what is the fenditure laterale • of Pavesi? According to the figure it must be .situated on the medial 



side of the organ, that is to sa}', it is presumably the ^sillon beaucoup plus petit et plus etroit» 



of Blainville; and thus it must be supposed to be the one seen in the skeleton, fig. i ay', and not 

 a > pocket) like the one described above in Lai/nia, because this latter is situated before the tenninal 

 part, and accordingly would be seen on the part called by Pavesi la meta basale». 



Rhinidce. 



Rhina squatina (L.). 

 (PI. II, fig. 24—27.1 



In a specimen of the length of i" and a breadth across the pectorals of 0,59'", the part of 

 the appendix free of the fin is S'/,'''" in length ; from the foremost beginning of the slit the length is 



■) Shaw; General Zoology V, pt. II, Pisces, 1804, tab. 149 (in the text notliiiig is found about it); the figure is 

 certainly bad, and the appendices can scarcely ever have that appearance, but are, to use the words of Pavesi (1878, p. 404), «tras- 

 formate in sorta di gambe dall'imaginoso disegnatore . Blainville gives it to be 7 inches long, but covered by soft tissues 

 except '2 inch, which m'a paru comme cornee et libre au bord superieur et exterieur de I'appendice >. Home speaks of 

 it as a strong, flat, sharp, bony process, five inches long, which moves on a joint, and the bone projects an inch and 

 a half beyond the skin, like a spur- (1S09, p. 207); in the later addition is only said: > the spur bears a striking resemblance 

 to that of the male omithorj-nchus paradoxus. • Lesueur: Description of a Squalus etc.; Journ. Acad. Nat. Hist. Philad. II, 

 part II. 1S22, p. 349; Mitchill in Dekay: Natural History of New York, Zoology, part IV, Fishes, 1842, p. 35S: .From and 

 between the anal fins, two legs project five feet in length, and are terminated by a claw tipped with horn >. Van Benedeu: 

 Un mot sur le Selache (Hannovera) aurata du crag d'Anvers; Bull. Acad. Roy. de Belgique, 2 Serie, vol.42, 1876, draws a 

 sketch of the appendices with the spur, from a stuffed specimen in British Museum, and shows that these spurs are (as 

 well as the giU-rakers) found as fossils in tertiarj- strata. Before I knew this fact and the paper by van Beneden, I have 

 expressed, in a lecture given in the Society for Natural Histor\- in Copenhagen (March 1897), the conjecture that the verj- 

 hard, « dentine-like < terminal pieces of the appendices of Selachii might exist as fossils, and indicated that perhaps some of 

 the (dchtyodorulites > were not dermal teeth (spines) but such skeletal parts; by turning over the work by Agassiz on 

 fossil fishes I have, however, not been able to find any drawing, to which this conjecture might be applied. 



2) Pavesi himself thinks the presence or absence of this latter to be dependent on the age of the animal, and not 

 to indicate a difference of species, and it is now beyond all doubt that this opinion is quite correct. AU other species of 

 Sharks tliat are pro\dded with a similar < spun (as Acatithias, Spinax, Somniosns a. o.) show that this piece is formed hidden 

 in the skin, and is not uncovered until it has reached a considerable degree of development, contemporary' with the organ 

 as a whole having altered its shape and dimensions. 



The Ingolf-Expedition. II. :•, " 



