54 



COE 



i8. AMPHIPORUS EXILIS sp. nov. 



pI. Ill, fig. 1 ; p1. vii, fig. 5 ; p1. xi, fig. 3. 



Body extremely elongated for the genus, rounded throughout ; not 

 capable of the great contraction which characterizes many species of 

 the genus ; only moderately flattened ; posterior extremity slender. 

 Head usually narrower than esophagal region. The general shape of 

 the body resembles that of Emplectonema. In shape of body, as 

 well as in color and habits, this species, like the 

 last, recalls A. lactifloreus (Johnston) Mcintosh. 

 Its anatomical structures are, however, very differ- 

 ent, as will be seen from the following description. 

 Ocelli. — Exceedingly numerous and minute. 

 They are arranged on the head in four elongated 

 clusters (fig. 14). Two of these clusters lie on each 

 antero-lateral margin of the head, while the two 

 other groups lie more posteriorly (just in front of 

 the brain), and extend from near the middle line 

 obliquely outward and backward. Sometimes the 

 two posterior clusters are united in front into a 

 continuous V-shaped group. The number and dis- 

 tribution of these eyes is indicated by the following table, which shows 

 the numbers found in ten individuals : 



I 

 Fig. 14. Amphi- 

 porus exilis. Dor- 

 sal view of head to 

 show arrangement 

 of ocelli. X 8. 



In the specimens examined, therefore, the number of ocelli in the 

 front clusters varied from 1 1 to 60, that in the posterior clusters from 

 15 to 73. The average in the 10 individuals is about 28 in each an- 

 terior cluster, and 41 in each posterior group. 



All the ocelli are minute, but nevertheless very irregular in size, some 

 being several times as large as others. From the ventral surface the 

 anterior marginal clusters only are seen. 



