REPORT ON THE SEALS. 181 



The variations in shape and alterations in size of the ventral surface of the ilium have no doubt 

 been the cause of the want of exactness and the difficulty in describing the iliacus. In Arctocephalus, 

 which is a near relation of Otaria, the ventral surface of the ilium is well marked ; in my specimen 

 it was fully an inch long and half an inch broad. In the large Phoca vitulina it was also well 

 formed, in a large Phoca grcenlandica it was half an inch long by half an inch broad. In the 

 small Phoca vitulina three-quarters of an inch long by quarter of an inch broad. In Phoca hispida 

 barely half an inch long by two lines broad, and in a specimen of Phoca vitulina in which the pubic 

 bar and the ilium were not fused it was only a border. In Macrorhinus the ventral surface was in- 

 creased by the broadening of the ventral border of the wing of the ilium, and the ventral surface and 

 broad ventral border were not recognisable as such, for the one was continued into the other. Meckel, 

 Humphry, and Murie agree as to there being an iliacus arising from the ventral surface of the ilium 

 in Phoca vitulina. Murie believes the iliacus is present in Otaria and Trichechus, but describes 

 it as coming from the spinal column as well as from the ventral surface of the ilium, and calls 

 it a serni-dividecl iliacus. Instead of naming this an iliacus, I have named the spinal fibres 

 psoas tertius, and the iliac fibres as the iliacus. In Macrorhinus only is there an iliacus without 

 a psoas tertius. In the Phocinas and in Arctocephalus the psoas tertius lies upon the iliacus, and 

 in the small specimens is intimately fused with it. 



The Ventral Femoral Eegion in the Phocinas, Macrorhinus Iconinus, and Arctocephalus gazella, 

 is composed of the tensor fascias femoris, sartorius, rectus femoris, vastus externus, and crureus. 

 The vastus internus and subcrureus are wanting. 



The Tensor fascim femoris in Phoca vitidina arises from the fascia lumbo-dorsalis in its inner 

 half, from the erector spinas in its outer half. It forms a band, which descends between the 

 anterior ventral spine and the posterior ventral spine of the ilium, just touching both. After 

 crossing the iliac crest it sweeps backwards, forwards, and inwards. Above the external condyle 

 of the femur it forms a tendon which is inserted into the deep strong fascia over the head of the 

 tibia and fibula. The tendon extends from the middle of the head of the tibia to the middle of the 

 head of the fibula, on the outer side, and into the lowest three-fourths of the edge of the patella. 

 In Phoca hispida the origin is similar. It is inserted into the outer edge of the patella, into the 

 outer edge of the ligamentum patellae, and into the head of the fibula to the dorsal side of the 

 ligamentum patellse. In Phoca barbata it arises from the fascia over the erector spinas only, and is 

 inserted as in Phoca hispida. 



In Macrorhinus it arises from the lumbo-dorsalis fascia, one inch and a half above the iliac 

 crest, and from the erector spinas. It descends over the anterior half of the crest of the ilium, 

 joins the dorsal border of the tendon of the sartorius above the patella, descends along its 

 outer edge to the tibia, and is inserted into the fascia over the head of the tibia, dorsally to the 

 sartorius. 



In Arctoccpludus gazella it arises from the fascia lumbo-dorsalis, three-quarters of an inch from 

 the spinal column opposite the middle of the space between the 3rd and 4th lumbar vertebrae to 

 opposite the spine of the 5th. The muscular fibres commenoe at the edge of the erector spinas. 

 It passes backwards and forwards to the knee, crossing between the ventral anterior and posterior 

 spines of the ilium, and is inserted by muscular fibres into the dorsal half of the patella, ending in 

 the ventral border of the ligamentum patellae. Lucae considers it as a muscle cover, otherwise his 



