206 -Mr. F. K. Ik.ldaid on 



Bothrioneuron americanum, .sp. ii. 



This worm was collected in oieat abundance, and i.s 

 described in a note by Dr. Michaelsen as havin;^ the ji^eneral 

 appearance of Tubifex. It was collected in the neighbour- 

 hood of" Buenos Ayres. 



The genus Bothrioneuron itself, to which I refer the present 

 species, has been lately described by Stole *. It differs 

 from all other Tubificidte, except Monopylepliorus oi \ji^.y\\\^^n^ 

 and Vermiculus of Goodrich |, in having an unpaired male 

 orifice. In his description of Monopylephoras Levinsen has 

 not referred to the spermathecal pores. As tiiese are absent 

 in Bothrioneuron it may be that the two genera are identical; 

 but it is impossible to be certain about the matter. These 

 three genera, moreover, agree with each other (and with 

 Lininodr'ilus and Clitellio) in having only uncinate sette ; 

 the capilliform setaj of other Tubificids are entirely absent. 

 The principal reason which leads me to place my new species 

 in the genus Bothrioneuron is the absence of spermathecge, 

 the absence of capilliform setse, the presence of an integu- 

 mental blood-plexus, and the existence of what Vejdovsky § 

 has termed a " paratritun,^' a diverticulum of the spermiducal 

 gland, to which, in Bothrioneuron Vejc/ovski/anuni, the prostate 

 is attached. Jn my species, however, the male pores are 

 double, but the paratrium apparently resembles that of 

 Bothrioneu7-on Vejdovski/anian. The atrium or, as 1 prefer 

 to call it, spermiducal gland is wrapped in a thick glandular 

 covering, as in the Lumbriculidc^i and the M<:)niligastrida3. 

 Such a coating aj)pears to be absent from Bothrioneuron 

 Vejdovskyanuni. In short, there is no doubt whatever as to 

 the specific distinctness of this worm ; the only doubt is as to 

 whether 1 am right in referring it to the genus Bothrioneuron 

 at all. I found no trace of the peculiar spermatophores 

 described by Stole, or, indeed, of any spermatophores at all. 



HESPERODRILUS, gen. nov. 

 Four species of Tubificids from Valdivia, Port Stanley, and 

 IJschuaia represent a perfectly new genus of Tubiticidai ; I 

 cannot refer them to any known genus. The most salient 

 characters of this genus are : — 



(1) The presence of capilliform setui only in the dorsal 

 bundles. 



« " Monoj^rntie Ceskvch Tiibitit-idii,'' Abb. k. J>bbui. Ges. 188^. 

 + " Systi'iiiati^k-frt'i <,n-uli^k Uversigt over de uordiske Aniuilata &c.," 

 Vid. Med. 1882, p. l"J:{. 



\ "Note on a new Oligocbspte," Znol. Anz. no. 408 (1892). 

 § " Sur lino Tiibilox d'Al^rtr'^rie," M(5in. Soc. '/ool. Fr. 18!»1. 



