520 Proceedings of the Royal Irish Academy. 
scription, takes origin from the tympano-hyal above the hypoglossal 
nerve, and is inserted as usual. Mylohyoid is transverse for nearly 
the whole length of the mandible. Styloglossus arising from the 
stylohyal arch passes forwards, overlying the hypoglossal nerve, and 
subjacent to the digastric muscle to be inserted as usual. 
Pectoralis major (0*42) bilaminar, the superficial portion taking 
origin from the front of the sternum, from the cartilages of the seven 
upper ribs, very slightly from the inner end of Ifie clavicle, and con- 
tinuous across the sternum with its fellow of the opposite side, 
runs forwards and outwards to be inserted into the second fourth of 
the pectoral crest of the humerus ; the deeper part with the same 
origin, is inserted into the upper third of the pectoral crest, is more 
tendinous, has its fibres more horizontal, and sends an upper slip to the 
capsule of the shoulder joint. Professor Macalister found its origin to be 
from the front of the sternum, from the cartilages of the six upper 
ribs, and distinctly from the inner end of the clavicle, the insertion was 
the same as in Arctopithecus, a condition which also existed in Pro- 
fessor Humphry's specimen, in which the origin was so mutilated as 
to be indistinguishable. 
Pectoralis minor is absent, as was also the case in the specimens dis- 
sected by Professors Macalister and Meckel. Professor Humphry 
describes it as arising from the second, third, fourth, fifth, and sixth 
costal cartilages close to the sternum. The fibres converge to a tendon 
which is quite distinct from that of the pectoralis major, and is inserted 
above it into the outer tubercle of the humerus," and remarks that it 
exists as represented by Cuvier and Laarillard. Professor Macalister 
however, considers that Cuvier' s pectoralis minor is really a subclavius. 
Subclavius ('02), arising from the first rib (in all), and passing 
outwards and upwards, is inserted into the clavicle and coracoid (Arc- 
topithecus) ; into the under side of the acromion process, and by a few 
fibres into the clavicle (Professor Macalister) ; slightly into the under 
surface of the clavicle but chiefiy into the inner edge of the coracoid 
process (Professor Humphry). 
Pectoralis quartus ('05) takes origin from the sixth, seventh, eighth, 
ninth, and tenth ribs, and is inserted into the top of the pectoral crest. 
Professor Macalister found it extending from the seventh and eighth 
ribs to the outer lip of the bicipital groove, and Professor Humphry 
describes it under the name of brachio-lateralis as being attached to 
the upper part of the pectoral crest, passing backwards under the pec- 
toralis major, closely connected with the seventh rib but mostly passing 
over it, expanding on the rectus and obliquus abdominis, and finally 
lost in the fascia about the knee. 
Sternocostalis arises from the fifth, sixth, and seventh ribs, and is 
inserted into the first rib. Professor Macalister describes it under the 
name of rectus thoracicus lateralis, as arising from the third, fourth, and 
fifth ribs, and inserted as above. Professor Humphry reverses our 
description of this muscle, giving its origin from the first rib, and its 
