44 coe 



of the pair of lateral nerve cords (pi. xiii, fig. 3), above the hind gut 

 and slightly in front of the anus. As seen from the figure, the union 

 of the blood vessels is directly dorsal to that of the nerve cords. 



The reproductive glands occur both above and below the alimentary 

 canal. Sexual products were not nearly mature in June and July. 



Habitat. The species is extremely abundant along the whole 

 Alaska coast as far west as Unalaska Island, and Stimpson records it 

 from Bering Strait. It is found under stones between tides in all sorts 

 of situations. Stimpson's specimens came from a depth of five 

 fathoms. The species is found on the Atlantic coast of North America 

 from Massachusetts Bay to Greenland (Verrill, loc. cit.). 



14. AMPHIPORUS BIMACULATUS. 



pi. 1, fig. 4; p1. v, fig. 10; pi. viii, fig. 2 ; pi. xii, fig. 2. 



Body rather short, broad, and flattened both above and below. Head 

 narrower than parts immediately following. Body of about the same 

 width and thickness throughout esophagal and intestinal regions. 

 Posterior extremity tapers rather abruptly to the pointed or rounded end. 

 Opening of rhynchodasum situated on subterminal portion of snout. 

 From near this opening a pair of slits pass obliquely backward and 

 upward behind the eyes to the brain region. 



Color. The color of this species is very striking. The whole dor- 

 sal surface back of the head is deep brownish orange, somewhat paler 

 behind. The head is without color, or of a very much paler color 

 than the rest of the dorsal surface, and in the center of this pale area 

 two oval, black or very dark brown spots lie side by side. These are 

 very characteristic, and are conspicuous even in alcoholic specimens. 

 The black spots sometimes occupy a considerable portion of the pale 

 area, and are sometimes sharply angular in front (p1. i, fig. 4). In the 

 median line of the body the color is slightly paler than elsewhere and 

 in the center of this paler stripe is a dark, but inconspicuous, longi- 

 tudinal line. The pale stripe and dark line both fade out at a point 

 about y^ the distance towards the posterior end of the body. The 

 brain lobes appear as pinkish bodies just posterior to the black cephalic 

 spots. The whole ventral surface is of a homogeneous, pale orange 

 or flesh color, with the exception of pinkish spots marking the position 

 of the brain, and a slightly paler stripe below the anterior portion of 

 the proboscis sheath. 



Ocelli. The eyes are rather large, and number 25 to 30 or up- 

 wards on each side (fig. n). The majority lie in an irregular margi- 

 nal row beside and in front of each of the black cephalic spots. At 



