PUNNETT AND FOESTEE COOPEE — NEMEETEANS. 11 



The excretory system begins soon after the mouth-region. There is more than one 

 duct on each side. 



The brain is comparatively large and has a well-marked dorsal lobe. The head-slits 

 reach halfway to the middle line and are not prolonged beyond the brain-region. 



Eyes and frontal organ are not present, nor could head-glands be distinguished with 

 certainty. 



18. Cerebratulus zebra, sp. n. (Plate 1. fig. 11 ; Plate 2. fig. 19.) 



Locality. Ceylon, from the pearl-banks of Azipu (Herdman Coll.). 



About 80 mm. of the anterior end of a rather large specimen, measuring 8 mm. in 

 breadth. 



The colour and pattern of the specimen, which is preserved in spirit, is characterized 

 by irregular transverse bands of dark greyish brown on a pale grey ground. In front 

 of the head-slits there are no markings and the ground-colour is somewhat paler. 



The intestinal region is much flattened and there are well-developed side folds. 



The epithelium (PI. 2. fig. 19) is very fuU of unicellular gland-cells and the base- 

 ment-membrane is exceedingly thin. A fairly well-developed circular muscular layer 

 is present beneath the basement-membrane, and the cutis-glands project into the outer 

 longitudinal muscle-layer. Pigment-granules occur chiefly among the circular cutis- 

 muscles, but they are also found to some extent in the epithelium. 



In the stomach-region the muscle-layers of the body-wall are all thick, the outer 

 longitudinal muscle-layer is twice as thick as the circular, which in its turn is twice as 

 thick as the internal longitudinal layer. Between the outer longitudinal and the 

 circular layers is a distinct diagonal layer. The horizontal musculature so often found 

 beneath the proboscis-sheath is here wanting. 



The mouth is small, and begins just behind the level where the cerebral organ ends. 

 The alimentary canal is of the usual Cerebratulus type. 



The vascular system shows a cephalic loop. The dorsal blood-vessel leaves the 

 proboscis-sheath a little behind the level at which the nephridial ducts are given off, 

 i. e., at the region where the nephridial system terminates. 



The proboscis is wanting. 



The excretory system possesses one pair of ducts, which open near its hinder end. 



The specimen is a male with ripe spermatozoa ; the genital ducts open on the dorsal 

 surface not far from the middle line. The head-slits are fairly deep, and extend about 

 halfway to the middle line ; they are somewhat prolonged past the mouth. 



A small frontal organ is present. There are no eyes. 



Head-glands are present, scattered through the musculature of the snout. /i^ .^ 



19. Biplopleura obocTciana (Joubin, 1887). 

 Locality. Wasin, British East Africa (Crossland Coll.). 

 Colour, when preserved in corrosive sublimate, white. Ties anterior ends together 

 with various fragments. 



