19 1 1.] J. Stephenson : Some Aquatic Oligochaeta. 205 



The dorsal vessel is very distinct in stained preparations, 

 extending along the whole length of intestine and stomach ; 

 it dilates on the dorsal surface of the oesophagus to form a 

 'heart,' coextensive with the oesophagus and in diameter equal 

 to it; the dorsal vessel can again be followed forwards from 

 the anterior end of the heart, over the buccal cavity, to which 

 it is attached as far as the anterior border of the mouth. 



The cerebral ganglion is conspicuous, fused with the epith- 

 elium of the dorsal surface of the prostomium. Thin strands 

 cross the cavity of the prostomium vertically, each with a 

 nucleus in the middle of its course ; strands attach the lower 

 surface of the cerebral ganglion to the epithelium of the ventral 

 surface where the latter turns inwards to become continuous with 

 the lining of the buccal cavity. 



The only species of Aeolosoma in which the oil-globules are 

 all of a green or blue-green colour are A. headleyi, Bedd., and 

 A. viride, Stephenson. From the former the present species 

 is distinguished by the setae being quite straight, and divisible 

 into two kinds, long and short ; from the latter by the deep 

 orange colour of the stomach, the division of the setae into 

 long and short, and apparently in the details of asexual multi- 

 plication (here n = 11, in ^4. viride n == 8). I therefore propose 

 the following diagnosis : — 



Length (preserved) i — 1"5 mm,, breadth '2 — '3 mm. Seg- 

 ments up to 16 (or ? more) ; n = 11. Setae all capillary ; bundles 

 consist as a rule of one long and several shorter, the long (210 y) 

 averaging twice the length of the shorter (no /j). Oil drops blue- 

 green. Oesophagus ii — iii, sinuous ; stomach iv — viii, deep orange. 

 Prostomium not broader than succeeding segments. 



Chaetogaster spongillae, Annand. 



1906. Chaetogaster spongillae, Annandale, Journ. As. Soc. 

 Bengal (N.S.), vol. ii, No. 5. 



Through the kindness of Dr. Annandale I received a few 

 specimens of the above species, discovered and described by 

 him a few years ago. The original account, however, deals 

 largely with the bionomics of the animal ; and a few additional 

 Qotes on its anatomy may therefore not be superfluous. 



The specimens which I received were all preparing to divide, 

 and it will be convenient to distinguish the anterior portion, 

 in front of the line of future fission, as A, the posterior, behind 

 it, as B. The whole animal, A + B, measured about '6 mm.; in 

 one case A measured •41, B -18 mm.; in another A was "39, 

 B '22 mm. ; in each case the pharyngeal region (as far as the 

 beginning of the oesophagus) was •12 mm. Even allowing for 

 contraction therefore, this appears to be the smallest species of 



