1869.] THE MYOLOGY OF MENOPOMA. 263 
partly from the postero-ventral border of the last branchial arch*, 
partly from the fascia of the side of the neck behind the branchial 
arches}. Thence it descends to the middle line of the body beneath 
the trachea, and above the sterno-hyoid, which latter is superficial 
to it. 
Genio-hyoideust (figs. 2 & 5, G. H). On removing the mylo- 
hyoidei, the two genio-hyoidei are seen running backwards (one on 
each side) from the symphysis of the mandible. Each genio-hyoid 
arises from the anterior part. of the ramus of the mandible of its own 
side (more or less connected with the submentalis), and is inserted 
posteriorly into the fascia, which also receives the insertion of the 
constrictor faucium. 
The cerato hyoideus externus (figs. 2 & 5, C. H. FE) is a con- 
siderable muscle which arises from the first branchial arch, and is 
inserted into the cornu of the hyoid towards its middle. 
The cerato-hyoideus internus (figs. 2 & 5, C. H. I) can hardly 
perhaps be reckoned a distinct muscle in Menopoma, in which it 
has a common insertion with the muscle last noticed. It arises, 
however, from the ventral segment of the second branchial arch. 
Constrictor arcuum (figs. 2,3, & 5, C. A). This small band- 
like muscle arises from the first branchial arch, and is inserted into 
the last two branchial arches. Fischer says§, no doubt correctly, 
that the muscle consists of two layers, the superficial one being 
inserted into the last branchial arch, and the deeper layer into the 
penultimate branchial arch. This muscle overlaps and binds down 
the constrictor faucium. 
The adductor arcuum (figs. 3 & 5, A. A) is a very small muscle, 
arising from the fascia on the ventral surface of the sterno-hyoid. 
Passing upwards and outwards, it goes to the last branchial arch. 
Sterno-hyoideus (fig. 2, St. H) A considerable muscular mass, 
which may conveniently be distinguished by this name], though in 
fact it is the anterior termination of that great ventral muscular 
mass which consists of the united internal oblique and rectus. Its 
insertion is into the posterior part of the under surface of the basi- 
hyal and the adjacent parts of the ventral segments of the branchial 
arches. 
The antero-internal portion of the ventral part of each sterno- 
hyoid shows a slight indication of distinctness as a muscular fasci- 
culus inserted into the fascia into which the genio-hyoideus is inserted. 
This appears to represent, in a rudimentary manner, the distinct 
muscle named levator maxille inferioris brevis by the Dutch 
authors]. 
* The hyo-trachealis of Fischer, /. c. p. 92. 
+ The dorso-trachealis of Fischer, /. c. p. 92. 
+ The levator maxillz inferioris longus of Schmidt, &c., see /. ¢. p. 29, pl. 6. 
fig. xii. 5. 
§ L.c. p. 75, and tab. 4. fig. 2, ca, 
| It is so by Dr. Fischer, see 7. c. p. 104, and tab. 4. fig. 2, sk. It is the 
cerato-hyoideus of the Dutch authors, Schmidt &c., see /. c. p. 30, pl. 6. 
fig. xiii. 9. 
§ See Schmidt &c., p. 50, and pl. 6. fig. xii. 6. 
