370 University of California Publications in Zoology. [Vol.6 



opening. On the ventral surface a line of scattered spines 

 streams off laterally and anteriorly from the tips of this semi- 

 circle to about the level of the receptaculum seminis. No spines 

 are found on the lateral frills. The arrangement of the spines on 

 the ventral surface (pi. 34, fig. 10) is a fairly constant one. It 

 is of interest when considered in connection with Lonnberg's 

 (1891) theory of the formation of the funnel and canal by means 

 of the partial fusion of folds of the ventral body wall. 



Gyrocotyle urna (Wagener) var. ? 



In the material collected by Dr. Kofoid near Monterey, off the 

 California coast in 1904. were found three specimens differing 

 from the rest in certain characters which seem to constitute a 

 basis for specific distinction. Later, in 1907-1908, the writer 

 found several similar specimens. The characters peculiar to this 

 form are as follows : 



1. The lateral frills are less voluminous. 



2. The folds of the posterior rosette are simple (i.e., not 

 thrown into irregular secondary frills, as in G. fimbriata), vary- 

 ing in diameter from one-sixth to one-third of the width of the 

 body. 



3. The lateral frills do not extend to the base of the rosette 

 but taper off gradually, disappearing posterior to the recepta- 

 culum seminis. 



4. Spines are present over the whole of the ventral surface 

 as far forward as the middle of the length of the uterus, and 

 extend thence in two lateral wings forward to a point just back 

 of the level of the opening of the uterus. There is no distinct 

 pattern discernible as in G. fimbriata. There are only a few 

 scattered spines on the dorsal surface, except around the 

 "collar," immediately in front of the base of the frill of the 

 posterior rosette. 



5. The relative position of the opening of the penis, uterus, 

 and vagina is markedly different from that seen in G. fimbriata. 

 (See measurements, p. 381.) 



Except in two particulars, i.e., the distribution of the spines 

 and the fact that penis and vagina open at approximately the 

 same antero-posterior level, this form seems to be identical with 



