630 Proceedings of the Royal Irish, Academy. 



observations have been made by Professors Henle and Macalister. 

 The linea semieircularis Douglasii which marks the level of the 

 entrance of the deep epigastric artery within the sheath of the rectus 

 abdominis is regarded by Retzius and by Hyrtl as the margin of a 

 fold of the fascia transversalis, which descends from that level to 

 cover the posterior surface of the bladder. "With the description of 

 these distinguished anatomists I cannot concur, and prefer to regard 

 the semicircular border as the lower edge of the aponeurosis of the 

 transversalis united with the posterior lamella of that of the internal 

 oblique, where they cease, to pass behind the rectus muscle. 



Transversalis abdominis. — The costal attachments of this muscle, in 

 twenty-nine of thirty-six cases, were six in number. In four the 

 attachment was to seven ribs ; in the remaining three the number was 

 reduced to five. Guthrie's description of the perforation of the lower 

 part of the muscle by the spermatic chord was verified by two exam- 

 ples, and I have also seen two or three others. The reflected fibres 

 described by Sir Astley Cooper as passing from the outer edge of the 

 conjoined tendon and reaching along Poupart ligament as far as the 

 internal ring, I have not found at all well developed in any case. 

 Only a few scattered muscular bundles can be found in the aponeuro- 

 tic process, which passes from the outer margin of the conjoined ten- 

 don, along the posterior wall of the inguinal canal. 



Rectus abdominis. — The variations of this muscle chiefly aiiect the 

 breadth, length, and number of tendinous inscriptions. The breadth 

 opposite the umbilicus I have found to vary from two and a-quarter 

 inches to three and three-quarters. I have traced some of the fibres to a 

 sternal insertion i]i two instances. In one case I noticed that the upper 

 attachment of the muscle was to the cartilage of the fourth and fifth ribs. 



The number of tendinous inscriptions varies from two to five, three 

 being the usual proportion. They were specially examined in sixty 

 cases. Of these, two presented absence of the xiphoid inscription, 

 those present being the umbilical and intermediate. I have also 

 observed this in two other subjects, in one of which the deficiency 

 was bilateral. The intermediate inscription was absent in one case, 

 and I have noted two other instances. In one case observed (not 

 included in the above sixty) there were five linese transversEe, two 

 being infra-umbilical. In five of the sixty cases one infra-umbilical 

 inscription was present, the degree of development varying greatly. 

 The umbilical inscription was invariably present. 



Doubling of this muscle on one side has been recorded by Otto ; 

 but this must be excessively rare. In some emaciated subjects I 

 have sometimes found one or two segments easily separable into two or 

 three fasciculi. 



Pyramidalis ahdominis. — This muscle I have carefully examined in 

 sixty subjects, In nine of these the muscle was absent on both sides. 

 In five subjects it was absent on one side only : in three of these the 

 deficiency was on the left side ; in two on the right. In six of the 

 subjects the left was obviously smaller than the right, the difference 



