83 



recognize with any degree of certainty that specific individuality, so 

 strongly insisted on in the able work so frequently cited. This diffi- 

 culty is, moreover, increased by the knowledge that some of the so-called 

 distinctive characters are possessed in common by all, while others are 

 so feebly developed that they may fairly be attributable more to the 

 varying conditions of life than to any essential structural quality. 



I instance the worn-down or truncated teeth, a singularity, not the 

 special property of any one, but equally belonging to all of the very 

 aged ; and to the slight deviations in the form of the cranium, which, 

 of themselves are so uncertain as to necessitate a continual revision of 

 the systematic arrangement. 



Beyond these methods but little remains to evidence any specific 

 differences among this group, with the exception, perhaps, of " locality" 

 the latter presenting but a false criterion by which any correct idea 

 can be arrived at of aquatic animals, so wholly unrestrained by any 

 barrier in their range of habitat. 



Genus LAGENOBHTNcmis, 1 Gray. 



Head convex, forehead low, gradually sloping into the beak ; beak 

 short ; beak of the skull very short, from to slightly less than, half of 

 the entire length of the skull, broad, depressed, narrowed in front, and 

 bent up in front of the maxillary notch ; symphysis of mandible short, 

 between -J- and i of the length of the ramus ; teeth moderately large. 



" This genus is easily known from Delphinus by the lowness of the 

 forehead, the short and depressed form of the beak, the posterior 

 position of the dorsal fin, the body being attenuated behind, and by 

 the breadth and flat expanded form of the nose of the skull." Gray, 

 S. & W. p. 268. 



* Teeth three in an inch. 



LAGENORHYNCHTJS ALBiEOSTEis, 2 Gray. The White-beaked Bottle-nose. 

 Synonyms Delphinus albirostris, Gray, 1846. 



Lagenorliynchus albirostris, Gray, S. & W.,p. 272; Suppl., 



p. 79. 



Teeth gpa, large, three in an inch. 



" Upper part and sides very rich deep velvet-black ; external cuticle 

 soft and silky, so thin and delicate as to be easily rubbed off ; the nose, 

 a well-defined line above the upper jaw, and the whole of the under 

 jaw and belly cream colour, varied with chalky white ; fins and tail 



Inhab: North Sea. Faroe Islands. Yarmouth. 



1 \dyTjvos & cup, a flagon, and f>vyx*> a beak, hence Bottle-nose. 



2 albits, -white, and rostrum the beak. 



