28 THE NECTURUS 



patches of mucous cells, divides them into a dorsal epaxial 

 and a ventral hypaxial series. Dissect into the muscle 

 layer of the body. 



Drawing 10. Make a diagram showing the direction of the fibers 

 of the different sheets. 



What is the function of this distribution of the fibers? 



MUSCLES OF THE PELVIS 



Drawing 11. Make a copy of the ventral view of the skeleton of 

 the girdle, with the limbs attached to be used in showing the origins 

 and insertions of the muscles. From the ventral face of the pelvic 

 plate, a number of muscles are seen extending out to the femur and 

 to the other bones. 



PUBOISCHIOTIBIALIS 



This posterior muscle of the pelvic region, covers the 

 other muscle of the anterior part of the girdle, the 

 puboishiofemoralis externus. It takes its origin from the 

 pelvic plate and is inserted on the tibia and ventral surface 

 of the foot. Note the raphe at about the middle of the 

 muscle as this is a good landmark. Distal to the raphe, the 

 muscle splits, a smaller slip extending to the fascia of the 

 ventral surface of the foot. This muscle is sometimes 

 called the semimembranosus, but it is really a part of the 

 undifferentiated muscle mass in Necturus. Near the raphe 

 a muscle is seen extending back to the caudal region. 

 Dissect away the soft material around the cloaca to expose 

 this muscle. This is an example of a muscle that has its 

 insertion on another muscle, a rather uncommon con- 

 dition. This tail muscle is called the pyriformis or better 

 the caudali puboischiotibialis. 



Separate the puboischiotibialis from the rest of the mass, 

 cut it through at the raphe and deflect to the two sides. 



