78 BULLETIN 3(5, UNITED STATES NA'IIUNAL JHiSEUM. 



to hold good, it willaidin distinguishing tliis gouus IVoui lAKjcnorhynchus, 

 Frodelphinus^ Tnrsioj)s^ and Delphinvs^ its nearest alHes. 



In the skull in the National Museum tlie free uiargius of the uiaxillae 

 behind the notch are thinned out as in )Sag)itatia.s. 1 neglected to note 

 this character in the skull in the College of Surgeons, and Van Beneden 

 and Gervais figure only the lower side of their specimen. 



The mandible of our specimen is remarkable for its extreme attenua- 

 tion anteriorly. It is bent downward and is not keeled anteriorly. In 

 Ouvier's figure of Z. peronii the mandible is bent downward, but is dis- 

 tinctly keeled {Oss.fossiles, 4th ed., pi. 222, figs. 5-G). . 



The scapula of L. peronii, figured by Cuvier [Oss. foss., 4th ed., pi. 

 224, fig. 20), is, as pointed out, remarkable for its width as compared 

 with its height. The acromion and coracoid are also very large. 



The genus may be provisionally defined as follows: No dorsal fin. 

 Pterygoids apart in the median line, at least at the base. MaxilUe not 

 thickened behind the notch. 



Two species are tolerably well known, the one, L. pcronii, from the 

 South seas, and the other, L. boreaJis, from the North Pacific. They may 

 be distinguished by their coloration, as follows: 



1. Beak aud pectoral fins white L. peronii 



2. Beak and pectoral fins dark, like the back L. horealm 



TURSIO PERONII (Lacepede). 



Delphinus peronVi, Lacdpede, Hist. uat. dcs Cetac6s, 1804, p. '31C. 



Dclphitnts leucorhamjihus Peron (MS.), /rfe Lacepede, Hist. uat. des Cetaces, 1804, 



p. 31f). 

 Leucorhamjihus peionii, Lilljeborg, Upsala Umv. Arsskrift, 1861, p. 5. 



Neither Lacepede nor Desmarest (Mjunmalogie, p. 517) seems to have 

 suspected that P eron's Dauphin levcorhamphe was without dorsal fin, but 

 Cuvier,* having obtained a skin from India through Dussumier, in 

 which the dorsal was absent, while the colors corresponded to those of 

 Peron's dolphin, concludes that the latter was finless. He identifies 

 his specimen with the D. peronii of Lacepede. 



Very few specimens of this species have been preserved, Tlie skull 

 figured by Vau Beneden and Gervais (Osteog. pi. 38, fig. 3) is presuma- 

 bly that received by Cuvier from Captain noussard,t though these au- 

 thors do not state that it is the same. I unfortunately tailed to see this 

 specimen when in Paris. Gray (Cat. Seals and Whales, p. 277) gives 

 measurements of a skull in the same museum "from Peron," but I think 

 that there must be some mistake regarding this statement. There is a 

 skull (No. 3029) in the College of Surgeons, London, which Professor 

 Flower has identified with this species. The four skulls (Nos. 17, 18, 

 19, 20) in the Leydcn Museum, which are labeled D. peronii, do not 



* Recherclies 8ur les Ossemens fossiles, 4'"" 6d., viii, pt. 2, 1836, p. 107. 

 t F, Cuvier has Homsart (Hist. nat. C6fcac6s, p. IG.'')). 



