ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 



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

 5,6 cra 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 Td 2 as in Lanuia. I found this opinion in the first place on the words of Blainville 

 (I.e. p. 126) that besides the claw there is un autre cartilage, uu 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 uu repli de la membrane interne qui se prolongeoit, libre 

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

 description (1S7S, p. 352) and drawing in woodcut (fig. 3) of the (undeveloped) appendix given by 

 Pavesi: nella meta apieale offrouo un pezzo mediano lanceolate, rialzato e piano, con fenditure laterali. 

 Ouesto superficie 11011 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 dermai fold mentioned 

 by these authors, 110 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 on 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 Lanuia, 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. 11, fig. 24 -27.) 



In a specimen of the length of i" 1 and a breadth across the pectorals of o,59 m , the part of 

 the appendix free of the fin is 8' /'" in length; from the foremost beginning of the slit the length is 



J l Shaw: General Zoology Y, pt. II, Pisces. 1S04, tab. 149 (in the text nothing is found about iti; the figure is 

 certainly bad, and the appendices can scarcely ever have that appearance, but are, to use the words of Pavesi ,iS;\ p. 404), tras 

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

 except l 2 inch, which 111'a paru comme cornee et libre an 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 (1S09, p. 2071; in the later addition is only said: the spur bears a striking resemblance 

 to that of the male ornithorynchus paradoxus. I.esueur: Description of a Squalus etc.; Journ. Acad. Nat. Hist. Philad. II. 

 part II. 1822, p. 349; Mitchill in Dekay: Natural History of New York, Zoologv. part IV. Fishes, [842, 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: 

 l'u mot sur le Selache (Hannovera) aurata du crag d'Anvers; Bull. Acad. Rov. de Belgique, 2 Serie, vol.42, 1 s 7 ' > . draws 1 

 sketch of the appendices with the spur from a stuffed specimen in British Museum, and shows that these spin 

 well as the gill-rakersl found as fossils in tertiary strata. Before I knew this fact and the paper by \ .1 11 Beneden, I have 

 expressed, in a lecture given in the Society for Natural History in Copenhagen (March [897), tin- conjecture that the 

 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 tinning over the work !>\ Agassi 

 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 lattei 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 specii 

 Sharks that are provided with a similar spur (as Acanthias, Spinax, Somniosus a. o.) shov that this pine is formed hidden 

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

 as a whole having altered its shape and dimension 



. The Ingolf-Expedition. II. .>. 6 



