ANATOMY OF THE SHOE-BILL. 



667 



a thin wide sheet of fibres which runs over the ventral surface, 

 meeting its fellow of the other side and forming a platysma 

 myoides, and a better defined band which runs across to be in- 

 serted to the ceratohyal, superficial to both divisions of the 

 geniohyoid. 



Geniohyoid. — Two Avell - marked divisions. A very strong 

 division arises from the last joint and cartilaginous end of the 

 ceratohyal, round which it is Avrapped, and runs forwards to the 

 outer surface of the lower jaw just under the orbit. The second 

 division arises from the first joint of the ceratohyal and runs 

 straight forwards as a sheet of fibres which meets the corres- 

 ponding fibres of the same division of the other side. These 

 fibres can be traced up to the junction of the rami of the 

 mandible. 



Genioglossus. — Probably in relation with the degeneracy of the 

 tongue, this muscle was absent. 



Geratoglossus. — Fleshy from the outer side of the first joint of 

 thei cei'atohyal to the tip of the tongue. There was no separate 

 tendon. 



The hyoid muscles, like those of the head, of Bcdceniceps were 

 excessively like those of the Pelican, but I attach no systematic 

 importance to the similarity, as I have very little material with 

 which to compare these muscles in a number of difierent groups, 

 and the material I have shoAvs that, apart from obviously adaptive 

 features, these muscles are much alike in Avidely separated groups. 



Caudal Muscles. 



Puho-coccygeus externus. — A flat band of muscle from the 

 posterior dorsal margin of the end of the pubis, narrowing to its 

 insertion on the under surface of the sheath of the external 

 rectrix. 



Puho-coccygeus internus. — This is a much wider and thinner 

 miascle, deep of the externus, and arising from a greater area of 

 the pubis with a reach on to the ischium. It is inserted to the 

 ha3mapoph3'Ses of the posterior caudal vertebrfe. 



Levator coccygis. — The two levators form a strong diagonal 

 mass of musculature on the dorsal surface of tlie tail, anteiior to 

 the oil-gland. They arise from the ilium and the lateral pro- 

 cesses of the caudal vertebrse and are inserted by a series of 

 tendinous slips to the spinous processes of the caudals and to the 

 membi'ane covering the rectrices. 



Deqyressor coccygis. — Arises from the transverse process of the 

 last sacral vertebra by a strong tendon just at the articulation 

 with the ilium, and from the transverse processes of the first 

 three free caudals ; insertion to the transverse processes and 

 hsemapophyses of the posterior caudals. 



Ilio-coccygeus. — Onl}^ the outer of the tAvo slips which usually 

 represent this muscle is present. It arises from the ilium just 

 dorsal to the origin of the depressor coccygis, and is inserted to 

 the outer surface of the capsule of the external rectrix. 



