I8»7.] ANATOMY OF HYDROMYS. 5/ 



This represents the intercoluninar fascia of human anatoni}'. From 

 the lower border of the combined internal oblique and transversalis 

 a number of muscular fibres pass on to the same process and sur- 

 round it as a series of rings nearlj^ to its lower end. There is a large 

 erector penis overlying the crus of either side, but no transversus 

 perinei. The bulbus urethrre is double, and each half is overlaid bv 

 a muscular sheet which joins its fellow of the opposite side in a 

 raphe on tlie lower surface of the penis ; posteriorly the two halves 

 unite behind the rectum, round which tube they form a kind of 

 sling. In the angle betw^een this last muscle (accelerator urinjp.) 

 and erector penis lies Cowper's gland. The psoas and iliacus 

 muscles are both large and differ in no respect from the normal. 

 There is no psoas parvus. Rectus abdominis is attached to the 

 second rib. 



Muscles of the Lower Extremity. — The exterior of the buttock is 

 covered by a large sheet of muscle arising from (!) crest of ilium, 

 (2) under the anterior superior spine of the ilium, (3) by means of 

 an aponeurosis from all the vertebras from the last lumbar to the 

 last sacral inclusive. It is inserted into (1) the third trochanter at 

 the middle of the femur; (2) the larger part into the fascia on the 

 outer side of the thigh and leg and the upper part of the patella. 

 As there is no separate tensor vaginse femoris or sartorius, this 

 muscular sheet would appear to represent these two in fusion with 

 gluteus maximus. Gluteus medius is very large ; its anterior fibres 

 are inserted into the outer edge of the great trochanter, its posterior 

 into the femur inferior and anterior to this process. Gluteus mini- 

 mus arises from the concavity of the ilium, and is inserted by tendon 

 into the upper part of the great trochanter. There is no separate or 

 intrapelvic ])yriformis; part of the fibres of the gluteus minimus 

 arising from the edge of the sacrum close to the sacro-sciatic foramen 

 aj)pear to represent this muscle. 



Biceps is very large, and arises (1) superficially from the up|)er 

 caudal vertebrae by fascia ; (2) deeper, from the' tuberosity of the 

 ischium. The two parts unite, and are inserted (1) by fascia into 

 the outer part of the patella; (2) by tendon into the process near 

 the head of the fibula ; (3) by fascia into the whole of the front of 

 the leg as far down as the back of the heel. Thus the entire of the 

 thigh and leg below gluteus maximus is covered by this large mus- 

 cular sheet. 



Semitendinosus is single-headed and arises from the tuberosity and 

 adjacent portion of tlie ischium ; it is inserted into the crest of the 

 tibia below the gracilis. Semimembranosus, which is very much 

 smaller than either of the other hamstring muscles, is inserted 

 into the upper part of the posterior aspect of the internal condyle of 

 the femur. 



Rectus femoris has a single tendon with a double attachment, viz. 

 under the acetabulum and to the margin of the ilium. There is a 

 scansorius arising from the entire of the anterior edge of the ileum. 



Pectineus consists of two distinct parts — (1) Internal, which is thin 

 and arises from the inner part of the linea ileo-pectinea, some of 

 its fibres underlying the outermost of gracilis ; this portion is inserted 



