1O12-] J. STEPHENSON » Indian Aquatic Oligochaeta. 229 
bundles of 4-6 setae, the distal prong of which is the longer in the 
most anterior segments, the proximal being the longer in the 
remaining segments. No stomach. Lynaph corpuscles rounded, 
with numerous olive-green granules. Asexual reproduction with- 
out the previous formation of a budding zone. 
2, B. menoni sp. nov. 
Length (preserved) 8-15 mm., segments up to 130. A short 
prebranchial region between first gills and mouth, which may 
or may not possess a series of pairs of ventral setal bundles (up to 4 
pairs). Gills diminishing in’ size posteriorly, and ending some 
distance in front of hinder end; longest gills 2} times as long 
as diameter of body. Dorsal setal bundles anteriorly of one or 
two hair setae; in the middle and posterior parts of the body 
of one hair and one needle seta, the latter somewhat bayonet- 
shaped, tapering to a fine point. The hair setae of the anterior 
bundles enclosed in the gills; becoming free before the 30th 
segment Ventral bundles usually of 3, sometimes of 2, setae; 
anteriorly slenderer, distal prong longer, nodulus proximal to 
middle of shaft or about its centre; further back the setae are 
stouter, distal prong approximately equal to or a little longer 
than proximal, nodulus distal to middle. Nostomach. Asexual 
reproduction without or almost without previous formation of a 
budding zone. 
3. B. hortensis (Stephenson) (—=Lahoria hortensis). 
Length 16—25 mm., diam. -5—'°75 mm., segments go-120. 
Gills and dorsal setae begin on sixth (occasionally fifth) segment. 
Gills diminishing in size posteriorly, ending just in front of hinder 
end of animal ; longest gills 3-4 times as long as diameter of body. 
Dorsal setal bundles of capillary and needle setae, not more than 
two of each per bundle; contained within the gills for the first 
40—50 segments, then one hair seta of each bundle free; needle 
setae straight, pointed. Ventral bundles of 4—-5 setae, distal prong 
slightly longer than proximal, and much thinner at its base. 
No stomach. A budding zone formed during asexual division. 
4. On Cephalization in the Naididae. 
Cephalization means the formation of a head; to quote from 
Beddard (2), “‘Lankester has applied this expression to the 
specialization of the anterior region of the body so frequently 
seen among the Oligochaeta.’”’ This specialization shows 
itself perhaps most prominently in the distribution of the 
setae ;—** all Oligochaeta show cephalization as regards the first 
segment of the body, which never possesses setae.” The Naididae 
which (except Chaetogaster} have regularly ventral setae in all 
segments from the second onwards, frequently lack dorsal setae in a 
number of the anterior segments, and there are thus in these cases 
