636 Proceedings of the Royal Irish Academy. 



muscle are not infrequent, but they seldom amount to marked peculi- 

 arity. The most remarkable I have met witli is an origin from the 

 anterior surface of the great sacro-sciatic ligament, close to the lesser 

 sciatic foramen. This I have seen three times. In one case the ac- 

 cessory slips formed a fleshy band of about three-quarters of an inch 

 in width, and about a line and a-half in thickness. The others were 

 hardly half so large. A distinct slip, arising fi-om the inner surface 

 of the ischium, above the level of the spine, was present in two sub- 

 jects examined, and the slip was symmetrically developed in one 

 case. 



Ohturator externiis. — This muscle is very firequently divided into 

 two layers by the obturator vessels and nerve. This division occurred 

 in four of twenty cases consecutively examined ; the upper smaller 

 portion taking origin from the horizontal ramus of the pubis. In a 

 somewhat smaller proportion of subjects a very intimate degree of ad- 

 hesion of the tendon to the capsule of the hip-joint was noticeable. 



Quadratus femoris. — Two cases of absence of this muscle have been 

 already published, as mentioned under the head of gemellus inferior. 

 I have found fibres of connexion passing from the latter muscle into the 

 upper edge of the quadratus. In three eases an accessory bundle of 

 muscular fibres took their origin from the tendon of the semimembra- 

 nosus, and a similar variety has been noticed by Mr. Kelly of this city 

 (quoted by Macalister). The lower border I have occasionally found 

 very closely adherent to adductor magnus. 



Semi-memhranosus. — The tendon of origin was observed in three 

 cases to consist of two completely distinct parts. In one the peculi- 

 arity was bilateral. A slip of insertion to the retinaculum ligamenti 

 arcuati has been noticed by Macalister, and I believe it to be of pretty 

 frequent occurrence, as I have observed it in a good number of cases. 

 A distinct slip to the fascia of the leg, forming a tensor fasciae suralis, 

 is mentioned by W. Krause. Of this I have met with one example. 



Bemi-tendinosus. — This muscle rarely presents any notable variety. 

 The tendinous inscription I have in one case found to be doubled ; in 

 a large number of cases it was interrupted, but never completely 

 absent. 



Biceps flexor auris. — I have already published two cases of absence 

 of the short head of this muscle. An accessory head arising fi'om the 

 upper part of the linea aspera has also been recorded, and since its 

 publication I have met with two other specimens of thi'ee-headed 

 biceps ; the accessory head arising, in one case, from the upper part 

 of linea aspera, and in the other from the internal condyloid ridge of 

 the femur. 



Of the variations of the tendon of insertion I have noted four 

 examples of a slip to the outer tuberosity of the tibia. A tendinous 

 band of three-quarters of an inch in breadth, passing to the tendo 

 AchilHs, came under my observation in one case : the subject had been 

 a very muscular one. 



Tensor fascim sifralis. — A slip from the biceps to the fascia, over 



