410 Haeris Hawthorne "Wilder, 



three muscles the ischiocaudalis is the most medial, and is also the 

 most distinct. It is clearly a differentiation from the most ventral 

 fibers of the trunk-tail muscles, and arises from them in such a 

 way that it is impossible to definitely distinguish its slips of origin 

 from those of the undifferentiated myotomic masses. In this region, 

 the ventro-caudal, a thin aponeurosis, attached to the haemal spines, 

 separates the muscle masses of either side from the mid-ventral 

 mass of caudal glands, and forms a groove for the lodgement of 

 the latter. From the dorsal surface of this the fibers of the muscle 

 in question take their origin, the haemal spines most directly 

 involved being the first three or four. From this origin the band- 

 like muscle runs along the side of the cloaca, and inserts into the 

 outer angle (tuberosity) of the osseous ischium. 2 ) 



The two other caudal muscles, Mm. caudalifemoralis and caudali- 

 puboischiotibialis, arise from a common origin and as a single bündle, 

 becoming distinct from each other anteriorly, and formiug two long 

 bands, like the former. The origin is in the form of a flattened 

 mass or sheet, extending antero-posteriorly, and arising from the 

 sides of the haemapophyses of the first three vertebrae provided with 

 such a process, usually the 22nd, 23rd, and 24th. As the haema- 

 pophyses in this region are long and so inclined that they almost 

 overlap, they form upon either side a practically continuous line of 

 origin. Proceeding anteriorly the two muscular slips become diffe- 

 rentiated and diverge somewhat to their insertions, points indicated 

 in each case by the name. M. caudalifemoralis inserts into the 

 shaft of the femur just distal to the projecting crista lateralis; 

 M. caudalipuboischiotibialis terminates in the raphe of the pubo- 

 ischiotibialis, at the posterior border of the muscle. 



3. Dorsal aspect ofpelvic girdle. 



M. puboischiofemoralis internus (piß). This large muscle 

 lies upon the internal (dorsal) surface of the puboischium, over the 



1) Physiologically considered , the origin and insertion of this, and 

 perhaps also of the caudalipuboischiotibialis, should he reversed, as the 

 point of least motion is found in both cases to be the pelvic girdle. In 

 accordance, however, with the anatomial structure the end associated with 

 the axial skeleton would form the natural point of origin and thus they 

 «re described here. This method has the distinct advantage of treating 

 all three closely associated muscles alike, whereas otherwise the course of 

 directum of one would be the reverse of that employed in the description 

 of the other two. 



