DESCRIPTIONS OF GENERA AND SPECIES 223 



This genus, which is in many respects a very remarkable one, is confined, so 

 far as our present knowledge goes, to California. Its anatomy has been described 

 by EisEN (2, 5) and by myself (81). The genus contains two species. 



Sutroa agrees with Rhynchelmis in its long and filiform prostomium; in many 

 other points it differs from that genus. In the first place the spermatheca is single 

 and median, and is furnished with numerous diverticula, which are both branched and 

 single. The very peculiar shape of the spermatheca in Rhynohdmis—^ecnM&x, that is 

 to say, as compared with other Lumbriculidae — suggests that one diverticulum is 

 present in the spermatheca of that genus; but in any case the multitudinous caeca 

 of Sutroa differentiate it from Rhynchelmis, even without going into any other 

 differences. 



There are, however, many other points of divergence between the two genera; it 

 is not certain whether there is in Rhynchelmis any communication between the 

 spermatheca and the lumen of the gut; Vejdovsky (5) speaks of 'einen Schlitz, 

 welcher den Eindruck einer Offnung macht, und in der That bemerkt man, dass unter 

 dem Druck des Deckglaschens auf das Organ nur auf dieser SteUe die Spermato- 

 zoenbiindel herausgehen.' Eisen (5), too, mentioned a pore at the extremity of the 

 spermatheca of >S'. alpestris. ' The object of such an opening,' he remarks, ' is not at 

 present understood.' I have, however, myself shown (81) that this aperture 

 communicates with the gut, though this discovei'y by no means explains the ' object ' 

 of the pore; it is, however, not unknown in other Oligochaeta (see p. 127). 



A comparison of Vejdovskt's (5) original paper upon Rhynchelmis with Eisen's 

 (2, 5) and my own contributions to the anatomy of Sutroa would indicate rather greater 

 differences than those that actually exist. Vejdovsky's most recent contribution to 

 the structure of Rhynchelmis is contained in his researches upon the development of 

 that Annelid (9). From this it appears that the differences are not, after all, so great ; 

 the spermiducal glands are, or rather may be, much greater in extent than is suggested 

 in the earlier paper; Vejdovskt writes that they may extend as far back as to the 

 thirtieth segment, and that they occupy the cavity of the sperm-sacs ; this is exactly 

 what occurs in Sutroa, though the glands are by no means so extensive ; they reach 

 back as far as the twentieth segment about, and are invested for the whole of their 

 course by the sperm-sacs. A curious point about the sperm-ducts of Sutroa alpestris 

 is that the anterior pair are much slighter than the posterior pair ; the funnel, too, 

 is less developed ; one is inclined to come to the conclusion that the anterior pair of 

 ducts is in course of disappearance, especially since there are no testes corresponding 

 to them. So far, therefore, Sutroa seems to connect the Lumbriculidae with the 

 Tubificidae, where there are, of course, only a single pair of testes and funnels ; but 



