Family IV. DELPHINID.E. 1 



"With dorsal fin ; head email, convex, moderately beaked ^eymphysis 

 of mandible moderate in length, never exceeding one-third of the 

 entire length of the ramus ; cervical vertebrae more or less anchylosed ; s 

 costo-steraal riba ossified. 



By a reference to the tabulated synopsis of the Cetacese, it will be 

 seen that I have limited the members of this Family to only a few of 

 the genera to be met with in Dr. Gray's last arrangement of 1871. 

 Even as now restricted it is very fertile in species, and some or other of 

 the individuals comprised within it may be met in almost every 

 imaginable part of the ocean, north and south of the equator, enduring 

 the extremes of heat and cold, disporting along the coasts, or within the 

 shallower waters of the bays, ascending the innumerable creeks and 

 inlets, or midway traversing the broad expanse of the sea, fleet and 

 voracious, ever in a state of activity 



" Or dire below, or on the surface leap 

 And spout the -waves, and wanton in the deep." 



The Delphinidae, of which the smaller members bear to each other a 

 most perplexing family likeness, are nevertheless made up of two 

 tolerably well-defined groups, typically represented by the common 

 dolphin and the common porpoise. The following general features 

 will sufliciently distinguish the two. In the group of which 

 the common dolphin is the representative, the head is more or less but 

 decidedly beaked, the beak being parted from the forehead by a 

 separating furrow ; the lower jaw is usually of greater length than the 

 upper one, and its symphysis moderately long. In the other section, 

 typified by the porpoise, the head tapers uniformly towards the lips, 

 scarcely, if at all, beaked, and without a divisional groove ; the jaws are, 

 in general, more of an equal length, and the symphysis of the lower 

 one comparatively short. 



"With these few preliminary remarks, I proceed, in the concise terms 

 to which I am limited, to the description of the genera and species of 

 the Family, following in general the order of arrangement proposed by 

 Dr. Gray ; but deviating from it on such occasions, where I think 

 the purpose I have in view is forwarded by a method of greater 

 simplicity. 



Genus SiEiro 3 , Gray. 



Head and forehead convex, moderately beaked ; beak of the skull 

 compressed, higher than broad, usually about & of the entire length of 

 the skull ; symphysis of lower jaw elongate, from i to i length of the 

 ramus ; fore fins moderately long, triangular, obtusely pointed at the 



1 From delphimis, a dolphin. 



2 Tursio truncatut eicepted ? 

 s <TTfi>os, narrow. 



