REPORT ON THE SEALS. 177 



the usual femoral attachment of the psoas maguus, but its position in the trunk and the want 

 of the trochanter minor in the Phocince and Maerorhinus, indicate that the niagnus must wander 

 to some other point, and it has settled on the posterior ventral spine of the ilium. The names 

 maguus and minor do not suit the magnitudes of these muscles in the Earless Seals, for the minor is 

 by far the larger, and the major along side of it is small, but it is convenient to keep the names 

 used in human anatomy. The tertius is a small muscle not to my knowledge previously described 

 in the Seals, and called the iliacus by Dr. Murie in Otaria. It is located upon the junction of the 

 lumbar with the sacral vertebras under cover of the other two muscles, and is directed obliquely over 

 the pelvic brim to the femur. It exists in all the specimens excepting Maerorhinus. The want 

 of a psoas magnus to the femur is compensated for by fibres springing from the posterior ventral 

 spine of the ilium, or from the pectineal eminence with, in some instances, a prolongation of fibres 

 from the psoas magnus into this group, or a direct offshoot from the psoas minor. The name ilio- 

 femorahs anterior is given when the fibres are only derived from the posterior ventral spine, and 

 ilio-femoralis posterior when from the pectineal eminence. In two specimens (small Phoca vitulina 

 and Phoca barbata) an addition is required to the name ilio-fernoralis anterior. The psoas magnus 

 in them gives fibres to blend with the ilio-femoralis anterior and then the name ilio-femoralis et 

 lumbalis anterior may be adopted. Lastly, in the large Phoca vitulina, the psoas secundus gives a 

 group of fibres directly to the femur, and this is called the lumbo-femoralis posterior. 



The Psoas magnus is called the psoas major and ilio-lumbalis by Lucae ; in Phoca vitulina it 

 arises from the sides of the ventral surface of the 3rd, 4th, and 5th lumbar vertebras to the inner 

 side of the psoas tertius, which it covers and crosses, to be inserted only into the posterior ventral 

 spine of the ilium. It has no ilio-femoralis anterior. 



In the small Phoca vitulina most of the fibres are inserted into the posterior ventral spine 

 of the ilium. It has an extension of its fibres forming an ilio-femoralis et lumbalis anterior. In 

 Humphry's account of this muscle he points out that some of the fibres pass to the inner side of 

 the thigh ; this is the group which Lucae figures as the femoralis major and has not described. 



In Phoca barbata this muscle has the same insertion and distribution as in the last species. 



In Plwca hispida it is inserted into the anterior half of the posterior ventral spine of the ilium, 

 and slightly into the adjacent inner half of the ventral border of the outwardly directed wing of the 

 ilium. There is a great difference between this muscle and the corresponding one in the small Phoca 

 vitulina, for not one of the fibres proceeds beyond the spine. It has, therefore, no lumbalis fibres 

 from the psoas magnus, but it has an ilio-femoralis anterior. 



In Maerorhinus leoninus it is inserted into the posterior ventral spine of the ilium, which is fused 

 with the pectineal eminence. 



In Arctoccphalus (jazella this is much the largest of the group. In the dorsal region it arises 

 by a series of muscular slips, from the posterior halves of the last four dorsal vertebra;, from their 

 intervertebral discs, and from the ventral surfaces of the ribs and the ligaments of the rib joints. 

 In the lumbar region it arises from the whole of the ventral surfaces of the 1st, 2nd, 3rd, and 4th 

 lumbar vertebra;, and from their intervertebral discs and transverse processes. It courses directly 

 backwards, above the psoas minor, to the outer side of the tertius, becomes narrower, and is 

 inserted into the posterior ventral spine of the ilium. There is no ilio-femoralis et lumbalis anterior, 

 or ilio-femoralis anterior, in this animal nor in Maerorhinus leoninus. 



The Ilio-femoralis et lumbedis anterior, in the small Plwca vitulina, is the ilio-psoas and ilio- 

 (zool. chall. exp. — part lxviii. — 1888.) Yyy 23 



