94 MR. R. c. PFNNETT OUT [May 21, 



circumference of the head. The openings of the cerebral organ 

 are ventro-lateral and rather in front of the organ. 

 Numerous eyes are present. 



Amphipoetjs aectious, n. sp. (Plate VII. fig. 9.) 



A single specimen from Davis Strait. Length 28 mm. and 

 greatest breadth 3-5 mm. The anterior end is slightly blunted ; 

 the posterior end tapers to a point. Colour a uniform pale buff 

 in preserved specimen. There is a weU-marked groove round the 

 head. 



The epithelium is about 70-80 mm. high, and contains a number 

 of small oval glandular concretions M'hich take a brilliant yellow 

 stain with picric acid. The basement-membrane is about half the 

 thickness of the epithelium in the oesophageal region. The circular 

 muscle-layer is well developed, its thickness being about the same 

 as that of the basement-membrane. The longitudinal muscle- 

 layer is also well developed. 



The vascular system is of the normal Amphiporid type. The 

 limbs of the cephalic loop lie closely apposed to the cerebral organ 

 in the region where this is present. 



The alimentary canal is more complicated than the usual 

 arrangement in the genus. It closely resembles that figured by 

 Joubin for A. marmomtus \ The ventral unpaired diverticulum, 

 however, is longer than in this last species, extending past the 

 median portion of the true blind gut. The blind-gut pockets do 

 not reach forward as far as the brain. 



The rhynchocoelom extends throughout the whole length of the 

 animal, being spacious even in its hinder portion. It reaches 

 backwards over the hind nerve commissure, a condition which is 

 apparently of rare occurrence according to Montgomery -. 



The proboscis is large and contains only 10 nerves. The arma- 

 ture has unfortunately been dissolved out. 



The excretory system extends forward past the brain to the 

 anterior level of the cerebral organ (Plate VII. fig. 9). The 

 backward extent of the tubules is, however, short. The excretory 

 duct is found on either side at the junction of the hindermost ^ 

 of the system with the rest. 



The genital sacs, which contain ova, are large and alternate 

 fairly regularly with the intestinal diverticula, a somewhat unusual 

 condition in the genus. They open just dorsally to the nervous 

 side-stems. 



The brain is well developed. 



The cei'ebral organ is small and is situated just in front of the 

 brain (Plate VII. fig. 9, corg.). Its greatest size in transverse 

 section is 150 fx in breadth and 200 fi in depth. 



Numerous eyes are present. 



The head-glands are well marked and extend backwards, though 



1 Joubin, L. : Archiv. Zool. Exp. et Gen. 1890, p. 564. 



^ Montgomery, T. H. : Zoolog. Jabrb., Abt. Syst. 1897, p. 4. 



