[27] OLIGOCH^TOLOGICAL RESEARCHES. 9Q5 



The eutiie ,si)iues resemble those of Enchytrai^ir. They are I'ouud 

 only in Telmatodrilus, and occur here in fascicles, of which four are found 

 in every segment. In each fascicle we find nine or more spines, all of 

 nearly equal length. In very young individuals the exterior end of 

 these spines show a tendency to forking, which, however, entirely van- 

 ishes by advanced age. 



Nearest related to these spines are the forked spines. They resemble 

 the former, except in regards to their exterior apex, which is forked. 

 Such spines occur in all the species of Tubificini. The angle of the 

 fork and the length and form of the prongs are important characteristics 

 of the species. The fork of the spines is oftentimes different in dif- 

 ferent segments of the same species. Such is the case in Psammoryctes* 

 and in Spirosperma (Fig. 20 ; 2 n.) 



Generally the prongs of the spine are only two, but in Spirosperma we 

 find three or sometimes even four (Figs. 2 «, 2 o, and 2^). Such spines, 

 however, are only found in the interior segments of the body. 



The forked spines are generally found in fascicles by themselves, but 

 sometimes also, as in Tuhifex and Semitubifex, alternating with hair 

 spines in the same fascicle on the upper side of the body. Forked 

 spines and fan-shaped spines are never found mixed or alternating in 

 the same fascicle. In Limnodrilus and Camptodrilus we find only forked 

 spines, but in all the other genera we find at least two kinds of spines, 

 viz, forked and hair spines. 



The hair spines are characterized by their length, oftentimes exceed- 

 ing the width of the body of the worm. They are only found on the 

 upper side of the body, and generally only in the anterior segments. 

 In Tuhifex and Hemitubifex they are found alternating with common 

 forked spines, but in Ilyodrilus, Spirosperma, and Psammoryctes mth fan- 

 shaped or pseudo-comb-like spines. The general number of spines in 

 such a fascicle is from five to six of each kind, varying, however, in the 

 different segments. 



The fan-shaped or comb-like spines are peculiar to the genera Psam- 

 moryctes, Spirosperma, and Ilyodrilus. They are characterized by hav- 

 ing a finely striated membrane stretched between the prongs of a forked 

 spine. There is, however, a difference between the prongs of a purely 

 forked spine and a comb-like one. Those of the former are always more 

 curved than the latter, which sometimes even are both bent either in- 

 ward, as in Psammoryctus, or outward, as in Spirosperma. The comb-like 

 spines are only found in the upper side of the segments, and always alter- 

 nating with hair-spines. 



As pseudo comb-like spines, I have designated spines the prongs of 

 which resembled those of the former class, but which were not con- 

 nected by any membrane whatever. The inner side of the prongs pre- 

 sented a strongly striated surface, evidently the first beginning of a dis- 

 tinct striated membrane. Such spines I have found only in the genus 

 Ilyodrilus (Figs. 5 e, 5/). 



* Vejdovsky, Ueber Psammoryctes, page 140. 



