ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 4I 



is claw-shaped and of a considerable size (in the specimen before me i6 cm long, and the broadest part 

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

 ment of several authors 1 ) the point of it (in the developed organ) projects through the skin. 



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

 been found, a Ti/ 2 as in Lamna. I found this opinion in the first place on the words of Blainville 

 (I.e. p. 126) that besides the claw there is tun 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 

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

 et flottante, jusqu'a l'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 

 Pave si: nella meta apicale offrono un pezzo mediano lanceolate, rialzato e piano, con fenditure laterali. 

 Ouesto 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» 2 ). The dermal fold mentioned 

 by these authors, no doubt corresponds with that one which in Lamna contains the piece Td 2 . But 

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



side of the organ, that is to say, 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. 12/, and not 

 a «pocket like the one described above in Lamna, because this latter is situated before the terminal 

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



Rhinidce. 



Rhina squatina (L-). 



(PI. II, fig. 24-27.) 



In a specimen of the length of i m and a breadth across the pectorals of o,59 m , the part of 

 the appendix free of the fin is S 1 //'" 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 nothing 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- 

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

 except ■ 2 inch, which ni'a paru comme cornee et libre au bord superieur et exterieur de l'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. (1809, p. 207); in the later addition is only said: < the spur bears a striking resemblance 

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

 part II. 1822, p. 349; Mitch ill in Dekay: Natural History of New York, Zoology, part IV, Fishes, 1S42, 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 Beneden: 

 Un mot sur le Selache (Hannoveraj aurata du crag d'Anvers; Bull. Acad. Roy. de Belgique, 2 Serie, vol.42, 1S76, 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 gill-rakers) found as fossils in tertian- strata. Before I knew this fact and the paper by van Beneden, I have 

 expressed, in a lecture given in the Society for Natural History in Copenhagen (March 1897), the conjecture that the very 

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

 the ichtyodorulites 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. 



-I 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. All other species of 

 Sharks that are provided with a similar spur (as Acantliias, Spinax, Somniosus 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. 2, o 



