718 MR FRANK J. COLE 



immediately behind the posterior border of the insertion of the copulo-palatinus into 

 the same. In the sections, the muscle arose almost exclusively from the fascia of the 

 internal angle of the ventral border of the tentacularis posterior. Even when its dorsal 

 border dips down so as to lose direct connection with the tentacularis posterior, it still 

 remains attached to it for some little distance by a ligamentous sheet. Again, in the 

 sections the dorso-anterior angle of the muscle does not reach the cornual cartilage, hut 

 it is connected with it by a short strong bundle of fibrous tissue, just where the cartiWe 

 fuses with the palatine commissure. No fibres arose, or could arise, from the palatire 

 bar, as the hyo-copulo-palatinus is widely separated from it at its origin by the copulo- 

 quadratus profundus and the palato-coronarius. 



J. MtiLLER states that the present muscle arises from the most anterior part of the 

 palatine bar in Bdellostoma, whilst in Myxine P. Furbringer asserts that it arises from 

 the posterior end of the cornual cartilage, and even from the palatine bar, and he 

 mentions finding in one specimen a bundle arising from the fascia of the copulo- 

 quadratus profundus. His fig. 5 agrees largely with what I have found. 



The fibres of the hyo-copulo-palatinus course downwards and backwards, somewhat 

 diverging, to be inserted as follows : — (a) a few fibres are inserted into the ventro-external 

 surface of the external bar of the anterior segment of the basal plate immediately below 

 the insertion of the copulo-quadratus profundus. In the sections the muscle was well 

 attached by fibrous tissue to about the ventral or inner half of the posterior sixth of the 

 external bar ; (b) two-thirds of the muscle are inserted into the ventro-external face of 

 the middle segment of the basal plate, in front near the outer margin, then passing 

 inwards about half way towards the middle line, and finally rising again behind so as to 

 be situated over or external to the insertion of the rectus muscle and to reach the root 

 of the first branchial arch ; (c) a large posterior bundle, representing the remaining 

 third, and which may be more or less distinct from the remainder of the muscle, as 

 shown in fig. 3, courses backwards and slightly downwards, slips under the antero- ventral 

 margin of the cranio-hyoideus, and in a 35 cm. Hag was inserted into the anterior 

 surface of the most ventral 3 mm. of the first branchial arch between the insertion of 

 the cranio-hyoideus and the origin of the hyo-copulo-glossus, i.e. external to the origin 

 of the latter muscle (q.v.). In the sections this part of the insertion is so confused 

 with the origin of the hyo-copulo-glossus that I could not satisfactorily separate them. 



The function of the hyo-copulo-palatinus is principally to draw the basal plate (and 

 hence the ventral margin of the mouth) upwards and forwards. 



23. M. copulo-quadratus superficialis. (Fig. 3, c. q. s.) 



J. MCller, Hinterer Vorwdrtszieher des Zungenbeins (p. 248). 

 ,, Hinterer Vorzieher des Zungenbeins (p 323). 



„ Zweiter Vorzieher des Zungenbeins (p. 324). 



P. Furbringer states that this muscle may in exceptional cases be either extremely 



