826 CLASS xin. 



of Zool. Soc. iv. 1851, pp. 26, 27. [From letters of VAN DER HOEVEN, 

 July and Sept. 1855, it appears that the above was no abnormity but the 

 usual conformation of the males. " I have had the opportunity," he adds, 

 " of examining recently two other male specimens, and hope to have time 

 to publish this year or the following, some new observations on the struc- 

 ture .... The male differs from the female by the absence in the mantle of 

 the lamellated glandular apparatus (OwEN's Mem. p. 43, PI. vin. fig. 10), 

 and by a different number of the digitations. (These are less numerous in 

 the female.) A chief difference, however, is the presence of the great 

 conoid body at the left side (see my Contributions, p. 27, PI. 7, figs. 10, n). 

 This singular body has at the extremity and on the outside a large disc 

 perforated by the orifices of numerous crypts. As the spermatophores 

 (NEEDHAM'S machines) after their passage through the penis are inclosed 

 in a bag formed of two coats, of a brown colour, and of nearly half an 

 inch in diameter, I believe that the glandular apparatus may secrete this 

 envelop, and that consequently it is a physiological analogon of the glan- 

 dular apparatus described by OWEN in the mantle of the female. The fold 

 connecting the labial processes at the inferior side above the funnel is in 

 the male of a different conformation, (see Contrib. pp. 26, 27). The fine 

 folds of the external labial processes are totally wanting, and instead of the 

 so-called olfactory organ at the commissure of the internal labial processes, 

 there is the cushion-like part (with 8 ir digitations), (Contrib. PI. 8, fig. 9). 

 As to the internal genital organs of the male, a large gland (testis), which 

 in bulk surpasses all the other organs of the body, except the liver, is 

 situated exactly where the ovary is in the female ; another smaller, flat 

 gland, more at the fore part, seems to secrete the spermatophora ; a bag 

 with an imperfect internal septum receives these spermatophorce and brings 

 them to the conical penis, which is situated not exactly, but nearly, as is 

 the vulva (more in the mid-plane)."] 



The genus Nautilus occurs also fossil in secondary and tertiary formations. 

 It is the only genus still extant of a very numerous division of the Cepha- 

 lopoda, which lived in the seas of a former world and of which the remains 

 are met with in mountain strata, especially in the older secondary forma- 

 tions. Here belong the Ammonites. 



Fossil genera related to Nautilus : 



Clymenia MUENSTER. 



Comp. Mem. sur les Clymenes et les Ooniatites du calcaire de transition 

 du Fichtelgebirge par le Compte DE MUENSTER, Ann. des Sc. nat., 2e SeYie, II. 

 1834, Zool. pp. 6578, PI. I. L. VON BUCH Ueber Goniatiten und Cly- 

 menien in Schlesien, Physical. Abhandl. der Berl. Akad. der Wissench. 1838 

 (section of genus Nautilus according to V. BUCH). 



Lituites BREYN, MONT. 



Sp. Lituites convolvans SCHLOTH., BRONN Lethcea gcoyn. Tab. I. fig. 3. 



Gampylites DESH., Cyrtocera GOLDFUSS. 



