ART. 15 ANATOMY OF THE EAEED AND EAELESS SEALS HOWELL 43 



but in the skeleton studied there was one, relatively as large as in the 

 Zalofhus, but in contact only with tarsale 1 — not with the centrale. 



In the otariid the four lateral metatarsals have responded to a 

 transverse crowding and proximad are flattened in this direction, 

 while the large hallux is very much flattened and transversely ex- 

 panded. The fifth is slightly more robust than the three middle 

 metatarsals. In the Phoca there has been equal or greater crowding 

 proximad but the metatarsals have been less responsive, interlock to 

 a much greater extent, and send a number of processes here and there. 

 Another result of this crowding of the tarsal elements is the slight 

 forcing in a plantar direction of the first, and more decidedly of the 

 fifth, metatarsals of the phocid. It is apparent that in the latter 

 there is some decrease in the mobility of the tarso-metatarsal articu- 

 lations. As with the otariid the fifth metatarsal is slightly more 

 robust than the three middle ones, and the first still heavier, but the 

 dilFerence in size is not so pronounced. In profile the dorsal outline 

 of the metatarsals in this genus, is markedly concave, to a conspicu- 

 ously greater degree in this animal than the otariid. 



In both animals the first and fifth digits are longer than the middle 

 three and in the otariid there is a tendency toward flattening of the 

 phalanges. Several investigators (as Kukenthal, 1890) have stated 

 that all except the terminal phalanges of the pedal digits of the pinni- 

 peds show distal as well as proximal epiphyses, in this respect ap- 

 proaching conditions in the Cetacea. As far as my own experience is 

 concerned, there is but one small juvenal Callm^himMs available which 

 seems to have nodules of bone in the cartilage of the toe joints repre- 

 senting distal epiphyses. All other individuals at hand are suiR- 

 ciently old so that no line of fusion at the distal ends of the phalanges 

 can with certainty be traced. The middle three digits of the 

 Zalophus have well-formed but slender nails, while those of the 

 first and fifth are rudimentary. In otariids there is a terminal 

 cartilage projecting in each pedal digit beyond the nail, and rather 

 scanty material leads me to believe, for the present at least, that 

 these cartilages are relatively longer in juveniles than in the adult. 

 In the Phoca the nails are better formed, those of the first and fifth 

 being larger than the other three. They project beyond the tips of 

 Ihe toes, as there are no terminal cartilages in this family. 



MYOLOGY 



In the following pages the comparisons are based upon the mus- 

 culature of the Zalophus dissected, notations being made upon the 

 muscles of the Phoca only when these showed details that differed. 

 Attention is called to points wherein Murie's Eumetopias and Odo- 

 henus, or Miller's ATk^tocephalus and Pho<}a differed from the condi- 

 tions in the respective families as I found them to be represented by 



