434 GRACE A. WELLS 



just postero-ventral to the palatal process (p.p.) and on either 

 side of the symphysis. Its origin is described in connection with 

 the account of the lateral surface of the cranium. The series 

 of five interbranchials have their insertions on the anterior mar- 

 gin of the cerato- and epibranchials (int.br. 1-5). The insertion 

 of the first of the medial system of interarculaes (m.int.arc.l) has 

 already been mentioned in connection with the ventral surface. 

 The remaining four (m.int.arc.2-5) are inserted on the postero- 

 medial surface of the pharnygobranchials. Each of the series of 

 the lateral system of interarcuales (/. int.arc.1-5) is inserted, 

 partly on the proximal end of its pharyngobranchial, and the 

 remaining fibers on a contiguous area on the epibranchial. 



The coracomandibularis (am.) has its origin in the ventro- 

 posterior surface of the lower jaw, in a restricted area on either 

 side of the symphysis. The coracohyoiedus (Chy.) is inserted 

 along the postero-ventral margin of the basihyal, while the first 

 of the series of coraco-branchials (c. br.) has its insertion on the 

 medial edge of the ceratohyal. The remainder of the series is 

 inserted on the proximal ends of the last four ceratobranchials. 



A small muscle, the adductor arcus branchialis (fig. 10, Aab.) 

 is attached on the internal surface of each gill arch at the lateral 

 hinge, one end being inserted on the distal edge of the cerato- 

 branchial, while the other is attached to the adjacent end of the 

 epibranchial. This small muscle belongs in the same series as 

 does the large, adductor mandibularis, mentioned above. 



