74 THE VOYAGE OF H.M.S. CHALLENGER. 



4. Transversalis abdominis. 



Le muscle trmisverse, Vicq d'AzjT, 1774, p. 490, No. 3. 



Der Querhauchmuskel, Merrem. 



Der Querbniwhmiislr'l, Wiedemann, p. 80. 



Der quere Buuchmushel, Tiedemann, p. 297, No. 3. 



Muscle transverse de I'abdomen, Meckel, vol. vi. p. 19, No. 3. 



Transversalis ahdominis, Owen, p. 31. 



Transversus abdominis, Selenka, vol. vL p. 105, No. 30. 



Le transverse, Gervais and Alix, j). 1 7. 



Attachments. — The transversalis abdominis arises from the whole length of the pubic 

 bone posterior to the origin of the internal oblique. The greater number of the fibres 

 pass transversely, but the anterior fibres pass downwards and forwards, while the posterior 

 fibres pass downwards and backwards. The fibres are inserted into the whole length 

 of the vertebral segment of the last rib, as well as into the abdominal aponeurosis, the 

 latter insertion extending from the sternum in front to within an inch and a half of the 

 anus behind. 



Action. — The muscles of opposite sides contracting simultaneously diminish the capa- 

 city of the abdominal cavity. 



Relations. — The muscle is concealed superficially by the obliquus externus and rectus 

 abdominis. 



Nerve supply. — Indirect branches of the lumbar plexus. 



Variations. — In one specimen of Aptenodytes the costal insertion of this muscle was 

 absent, although in other specimens of the same species it was present. In Spheniscus. 

 mendiculus also the costal insertion was wanting, the muscle being inserted exclusively 

 into the abdominal aponeurosis. In Spheniscxis minor, although the specimen which I 

 dissected was in excellent preservation, I failed to recognise the piresence of the transversalis 

 abdominis. 



5. Rectus abdominis. 



Gerader Bauehmuskel, Merrom. 



Gerader Bauehmuskel, Wiedemann, p. 80. 



Der gerade Bauehmuskel, Tiedemann, p. 297, No. 4. 



Le muscle droit de Vahdomen, Meckel, vol. vi. p. 20, No. 4. 



Droit du bas-ventre, Cuvier, vol. i. p. 217. 



Rectus abdominis, Owen, p. 30. 



Rectus abdominis, Selenka, vol. vi. p. 103, No. 27. 



Grand droit de Vahdomen, Gervais and Alix, \). 1 7. 



Attachments. — The rectus abdominis consists, as pointed out by Gervais and Alix, of 

 two distinct muscular slips. 



The internal slip arises from the abdominal aponeurosis, midway between the sternum 



