CHARACTERS OF PINNIPEDIA. 6 



Limbs piuuiform, or modified iuto swimming organs, nnd enclosed to or 

 beyond the elbows and knees within tbe common integument. 

 Digits of the manus decreasing in length and size from the first 

 to the fifth ; of those of the pes, the first and tiftli largest and 

 longest, the three middle ones shorter and subequal. Pelvis 

 with the iliac jjortion very short, and the anterior border much 

 everted; ischia barely meeting by a short sjanphjsis (never 

 anchylosed) and in the female usually widely separated. Skull 

 generally greatly compressed interorbitally ; facial j)ortion 

 usually short and rather broad, and the brain-case abruptly ex- 

 panded. Lachrymal bone imperforate and joined to the maxil- 

 lary, enclosed wholly within the orbit. Palatines usually sepa- 

 rated by a vacuity, often of considerable size, from the frontals. 

 Tympanic bones separated also by a vacTiity from the exoccipit- 

 als. Dentition simple, generally unspecialized, the molars all 

 similar in structure. Deciduous dentition rudimentary, never 

 truly functional, and generally not persistent beyond the fcetal 

 stage of the animal. Permanent incisors usually f or f, some- 

 times '*i {Cystopliora and MacrorMnus), or even f (Odohcenus); 



canines i ; molars * | , f , or f PINNIPEDIA. 



A. Hind legs caiiiable of being turned forward and iised in terrestrial loco- 

 motion. Neck lengthened (especially iu family II). Skull with 

 the mastoid processes large and salient (especially in the males), 

 and with distinct alisi^heuoid canals. Anterior feet nearly as 

 large as the posterior, their digits rapidly decreasing in length 

 from the first to the fifth, without distinct claws, and with a 

 broad cartilaginous border extending beyond the digits. Hind 

 feet sucej)tible of great expansion, the three middle digits only 

 with claws, and all the digits terminating in long, narrow, car- 

 tilaginous flaps, united basally. Femur with the trochanter 

 minor well developed Gressigrada. 



I. Without external ears. Form thick and heavy. Anterior por- 



tion of the skull greatly swollen, giving support to the enor- 

 mously developed canines, which form long, protruding tuska. 

 Incisors of deciduous (foetal) dentition {} ; of permanent denti- 

 tion . K o j)ostorbital processes, and the surface of the mastoid 

 processes continuous with the auditory bullse Odobcenidce. 



II. With small external ears. Form slender and elongated. Ante- 



rior poi-tion of the skull not unusually swollen, and the canines 

 not highly specialized. Incisors of deciduous dentition f , only 

 the outer on either side cutting the gum ; of permanent denti- 

 tion 1, the two central pairs of the upper with a transverse 

 groove. Postorbital processes strongly develoi^ed. Surface 

 of the mastoid processes not continuous with the auditory 



bullae Otariidw. 



B. Hind legs not capable of being turned forward, and not serviceable 

 for terrestrial locomotion. Neck short. Skull with the mastoid 



* In view of the uncertainty respecting the proper notation of the grind- 

 ing teeth, they will in the present work be designated simply as molars, 

 "with no attemx>t at distinguishing "premolars" from "molars." 



