146 



COMPARATIVE ANATOMY 



segmented off secondarily (Fig. 98) : it is perforated by nerves, 

 and gives rise on either side to an iliac process (most marked in the 



Holocephali) extend- 



Cep ing upwards into the 



lateral walls of the 

 body (Fig. 105). A 

 prepubic process is also 

 present, and there is 

 apparently also an in- 

 dication of a median 

 epipubic process (cf. 

 in fret}. The whole 

 pelvic plate essentially 

 corresponds, more or 

 FIG. 105. DIAGRAM OF THE ELASMOBKANCH PELVIS. less completely, with 



From the ventral side. 



the 



of 



ischiopubis 

 Bus, Pro, Rad, basipterygium, propterygium, and higher forms. 



radii of the fin ; BP, pelvic plate (ischiopubis) ; J n the Dipnoi the 



Oep, epipubic process ; Fo l . obturator foramen ; , -i 



cartilaginous 



7, iliac process; PP, prepubic process; 

 region of the ischiopubic symphysis. 



fly, 



narrow 



pelvic plate (Fig. 106) 



is provided with a long 



and delicate anterior median, a short posterior median process, 



and two pairs of lateral processes. Of the latter the anterior 



(prepubic processes) are much 



longer in Protopterus than in 



Ceratodus, and each is embedded 

 intermuscular septum ; 



n an 



with the posterior process the 

 skeleton of the fin is articu- 

 lated by means of an inter- 

 mediate piece. The anterior 

 unpaired process may be looked 

 upon as an epipubic process, 

 corresponding with that of Am- 

 phibia and Amniota (q. v.}. The 

 posterior or hypoischiatic process 

 bears a ridge for the attachment 

 of muscles. 



Amphibians. It will be 



seen by a glance at Fig. 104 D, Fu! 1()(i _p ELVIS()F Protopfeni ,<. From 

 that the ventral portion of the 

 pel vie arch of Necturus is formed 

 on the same plan as the pelvic 



plate Of the Dipnoi and CrOSSO- 



.. , , ii TT 11 j 



pterygll, but 111 all Lrodela and 



Amniota it is perforated by the 

 obturator nerve. Like the pelvis 

 of all Vertebrates, it has a paired origin, and in Proteus and 



the ventral side. 



prepubic p rocess , which may become 

 forked at its distal end ; b, process to 

 which the pelvic fin (HE) is attached ; 

 c, epipubic process; Gfr, ridge tor 

 attachment of muscles ; M, myotomes ; 

 M l , intermuscular septa. 



