212 W. BLAXLAND BENHAM. 
marked anteriorly and posteriorly, where it is dull pale 
yellow. They are very active little worms. I have found 
them not only in the Thames, but in the Cherwell, just above 
Oxford. 
Nais elinguis, O. F. Miiller. 
In a gathering from a ditch in the immediate neighbour- 
hood of Oxford I found, together with a number of specimens 
of Chetogaster diastrophus, Gruithuisen, some Naids 
showing zones of budding. A glance at the dorsal chetz of 
these latter determined the species as N. elinguis. 
It may be useful to recall the characteristic chetz of this 
species. In addition to the long capilliform chetz of the 
dorsal bundles (fig. 38, a), which commence on the 6th seg- 
ment, there are short needle-like forms, and a third kind, a 
straight spear-like cheta notched at the free end, with a swell- 
ing or node on the stalk at about one third or one fourth from 
the free end. There are usually two capilliform, two or three 
short needles, and two notched spears. The ventral chete 
present no important characters (fig. 38, 6). The blood is red, 
asin Paranais littoralis and other species. 
These specimens were gathered on May 10th of this year 
(1891), and were then actively reproducing asexually. They 
were, after examination, placed in a greenhouse; and on the 
26th of May, when I examined them again, most of them 
were sexually mature, whilst some were still showing zones of 
budding. 
In these asexual forms 1 find generally that n= 18, 
according to Professor Bourne’s use of the letter ;! but one 
case I noted in which n = 15. 
The sexual worms agree, in respect of the position of the 
organs, with Stylaria: that is to say, there is a pair of testes 
in Somite v, in which also are situated the spermathece ; a pair 
of ovaries in Somite v1, in which are also placed the atria and 
their apertures. 
The sperm-sacs have the arrangement shown in fig. 39; 
? “ Notes on Naidiform Oligocheta,” this Journal, vol. xxxii, p. 335. 
