l62 COE 



with swollen, rounded posterior end. As shown in pi. xxi, figs. 16-23,- 

 there is considerable variation in size and shape of basis. Figs. 22 and 

 23 were drawn from two specimens of the same color variety collected 

 at the same time, and yet the difference in size and shape of basis is 

 greater than commonly occurs between two related species. The 

 central stylet is of moderate proportions, not particularly sharp, and is 

 usually a little more than half as long as basis. There are commonly 

 three stylets in each of the two lateral pouches, although there are 

 sometimes four, or occasionally only two in one or both of the pouches. 

 Measurements of several specimens show the following variations : 



Length of Basis. Diameter of Basis at Widest Part. Length of Stylet. 



.17 mm. .10 mm. .08 mm. 



.15 .08 .09 



.14 .07 .08 



.14 .06 .07 



.13 .05 .08 



.11 .05 .07 



.11 .05 .06 



The length of the longest basis measured is therefore more than 

 half as long again as the shortest, while the diameter of largest is just 

 twice that of smallest. The length of stylet, on the other hand, is 

 much less variable, the longest being only half as long again as the 

 shortest. 



The posterior portion of basis is dark and granular (pi. xxi, figs. 

 1 6, 17), but gradually assumes the usual translucence in the anterior 

 half. 



Body Walls. Integument and musculature as in related species. 

 Pigment of dorsal surface situated among the basal portions of the 

 integument. Basement layer of body walls thicker than in most 

 species of the genus, and the species is also peculiar in having a rather 

 large amount of body parenchyma separating the organs of the body. 

 This parenchyma extends forward into the head in front of the brain. 



Cephalic glands are fairly well developed and surround the rhyn- 

 chodaeum on all sides, but they do not extend back as far as the brain. 

 Submuscular glands are wanting. 



Alimentary CanaL The rhynchocoel separates from the esopha- 

 geal opening well in front of the brain, so that the rhynchodaeum is un- 

 usually short. When the proboscis is partially extruded, the esophageal 

 opening (mouth) appears almost like a separate aperture. A pair of 

 slender diverticula of the intestinal caecum reach forward to the dorsal 

 brain lobes. They extend backward above the lateral nerves for some 



