276 Memoirs of the Indian Museum. [Voi,. I, 



Stylaria lacustris, ly. (PI. xix, fig. 46.) 



A single specimen of Stylaria was observed, of which the following is a short 

 description : — 



The worm was very active, resembling certain insect larvae in its quick wriggling 

 movements. Under the microscope, it was transparent The long proboscis-like 

 frost omium is shown in the figure (fig. 46) ; eyes were present ; the posterior end of 

 the body was provided with sensory " hairs." The specimen was preparing to 

 divide asexually, the anterior half having 21, the posterior 22, segments; the region 

 around the site of division was darker and less transparent, and the skin was 

 thicker here. 



The dorsal setae began in the sixth segment, were capilliform, smooth, in 

 length equal to the diameter of the body, or somewhat shorter than this ; they were 

 two, or sometimes three, per bundle, but of these only one in each bundle was of 

 the full length given above. The ventral setœ occurred in all segments from the 

 second onwards ; while more or less of the usual type, the proximal prong of the 

 fork was very small, and the nodulus distinctly one-sided [v. fig. 47) ; there were five 

 or six in each bundle. 



A few brown corpuscles were present in the body -cavity. The pharynx occupied 

 the region from the second to the fifth segment inclusive ; the stomach was a slight 

 dilatation in the eighth ; the intestine showed the usual antiperista!sis, and ciliary 

 motion in its posterior portion. The hlood was colourless; there were no blood- 

 corpuscles. The first nephridium occurred in the ninth segment (as in Pristina, not 

 as in Nais and Slavina). The posterior horns of the cerebral ganglion were much 

 elongated, and the anterior portion of the mass was of a more granular appearance 

 than the rest (fig. 48). 



Though no reproductive organs were seen, the above description, so far as it 

 goes, corresponds to that of 5. lacustris, L., and is perhaps of interest as being 

 probably the first record of the genus from the Punjab. Up till 1900, at least, it had 

 been recorded only from Europe and North America. 



General Remarks on the foregoing species. 



Though most of the species described above are already known, I have given 

 somewhat detailed accounts of them, because it may be of interest to compare 

 descriptions even of the same species from widely distant countries ; and because in 

 some respects, e.g., the reproductive organs, our knowledge of the anatomy of the 

 Naididae is still defective. 



Besides referring to the interest of the fact of the occurrence of the forms in the 

 Punjab, I may be allowed here to mention the following points, brought out in the 

 above descriptions, which, though not in all cases new, seem to me to merit 

 notice : — 



(i) The very variable and irregular thorn-Hke projections on the dorsal 

 setae of several forms, and their probable cause. 



