626 CLASS XVII. 



+t With head congruous, not surpassing the seventh part of trunk. 

 (Blow-hole single.) 



Monodon L., Ceratodon Beiss., Illig. Two horizontal canine 

 teetli in the upper jaw, in females mostly latent, enclosed, in males 

 that of the left side exsert, very long, straight, subulate, porrect, 

 grooved spirally, that of the right side concealed, solid ; two other 

 small teeth (spurious molars?) contained in the gum of upper jaw. 

 Lower jaw edentulous. Cutaneous fold scarcely distinct, in place 

 of dorsal fin. Transverse caudal fin, bilobed. 



Sp. Monodon Monoceros L., Lacep. Cetac. PI. 4, fig. 3, PI. 5, fig. 2, Blu- 

 MENB. Abh. naturh. Gegenst. No. 44, Scoresby Account, 11. PI. 15, figs, i, 

 ■2, Camper Cetac. PI. 29 — 31 (cranium); the Narwhal; this species lives in 

 the icy sea and feeds principally on cephalopods or sepise. It attains a 

 length of thirteen feet, besides the long tusk of the male, which may be 

 from eight to ten feet long. The tooth of the right side, which lies con- 

 cealed in the jaw, is externally smooth and not hollow within. Comp. 

 Home Led. on comp. Anat. 11. PI. 42. The two small teeth noticed amongst 

 the generic characters were discovered by Prof. Cl. Mulder ; compare his 

 valuable paper in the Tijdschr. voor nat. Geschied. en Physiol, il. 1835, bl. 

 65 — 109, PI. 2. In the females both teeth usually remain latent. Occa- 

 sionally Narwhals have been met with having two projecting tusks, but all 

 the instances are not examples of it which were cited as such by Albers 

 on the occasion of his describing one from the cabinet of Froriep : Icoiies ad 

 ill. Anat. comp. Lipsise, 1818, Tab. 11. iil; compare G. Vrolik in Bijdragen 

 tot de Dierkunde, published by the Society of Amsterdam, 3e Aflev. 1851, 

 bl. 21 — 28, with large figures. 



DelpMnus L. Teeth conical, vertical, mostly numerous in both 

 jaws. Caudal fin emarginate. 



Hyperoodon Lac, Uranodon Illig., Chcenodelphinus Eschr., 

 Wagn. Head rounded, with forehead declivous, produced abruptly 

 into a short snout. Gape of mouth small. Teeth covered by 

 gum. Blow-hole transverse, lunate, concave anteriorly. Adipose 

 fin remote, small ; pectoral fins small. 



Sp. Delphinus edentidus Schbeb., Hyperodon hictskopfLACEP. {a,ni. Delphinns 

 diodon ejusd.), Lac. Cetac. PI. 13, fig. 3, Schbeb. Sdugth. Tab. 346, 347, 

 348, fig. I, Hunter Philos. Transact, for 1787, PI. 19, [great Bottle-nose 

 Whale), Wesmael Notice sur un Hyperoodon, PI. i. M6m,. de VAcad. royale 

 de Bruxelles, xiii., W, Vrolik Natuur- en Ontleedkundige Beschouwing van 

 den Hyperoodon, PL i. Nat. Verhandel. v. d. Maatschappij der Wetensch. te 

 Haarlem, V. i. 1848, &c. (Figures of the skull in Camper Cetac. PI. 13 

 — 16, W. Vrolik 1. 1. PI. v — vii. ; of the brain by Eschricht in his paper, 

 cited at p. 597, n. x, PL viii.). The adult animal appears to attain a length 

 of from twenty-two to twenty-eight feet. In the skull the two erect ridges 

 are especially observable, which the upper jaws present near the forehead. 



