454 TEANSACTIONS LIVEKPOOL BIOLOGICAL SOCIETY. 



front of the brain this Nemertine agreed with Amphiporus 

 lactifioreus, but on a careful comparison of the two, certain 

 definite points of difference were invariably found. There 

 was a marked difference in the shape of the head, which 

 in A. lactifioreus is a rather long oval with the greatest 

 width just behind the lateral notches where the anterior 

 furrow passes from the dorsal to the ventral surface ; in 

 A. dissimulans the head is more lozenge shaped, there 

 being a distinct angle at the widest part which is just i)i 

 front of the lateral notches of the anterior grooves ; thence 

 the width decreases very distinctly as far as the lateral 

 notches formed by the posterior furrows, so that there is 

 a very distinct "neck." Another point of difference 

 concerns the arrangement of the eyes, which is very 

 characteristic in A. lactifioreus, where they are invariably 

 broken up into two distinct groups on each side, the 

 posterior group usually situated over the brain and 

 separated by a considerable interval from the anterior 

 series; while in A. dissimulans the eyes are arranged in 

 a continuous series on each side of the head, a few usually 

 extending inward towards the middle line in the region of 

 the anterior cephalic furrow. The smaller specimens at 

 Port Erin measuring 6 to 9 mm. in length usually had 8 

 to 10 eyes on each side ; one 6 mm. long was noted having 

 as many as 14 eyes on each side, but this number was 

 generally found only in specimens of 2 to 3 cm. The 

 most posterior eye of the series was generally situated a 

 little in front of the brain, in no case were eyes observed 

 actually over the brain. 



The figure given by Joubin to represent the head of 

 Amphiporus pulcher id, p. 129) gives a fairly good idea of 

 the arrangement of the cephalic furrows in A. dissimulans ; 

 the anterior furrows usually bend more forward on the 

 ventral surface so as to run closer to and more nearly 



