102 REV. HILDERIC FRIEND OX 



segments. No penial setse present ; no penis present." A further note is 

 added, " Posterior setse with upper tooth smaller than the lower : the node at 

 the outer third." I have material still under observation in the hope of 

 finding specimens in the adult condition. In my judgment Vermiculus 

 (Goodrich) and Bothrioneuron (^to\c= Bothrioneuriim as corrected by Michael- 

 sen) are synonyms of Monopylepliorus. 



The genus Limnodrilus has, perhaps more than any other, grown under my 

 investigations. I have not only to record the occurrence of the species which 

 have long been known to science, but venture to submit some new descriptions. 



8. Limnodrilus hoffmeisteri, Claj:). 



The most widely distributed species in the genus. Found almost every- 

 where in the Thames Yalley where mud can be obtained perennially. 



[Since I began the preparation of this paper I have had further oppor- 

 "tunities of studying this ubiquitous species. I find that the Thames 

 specimens taken at the Tower Bridge and elsewhere show one or two strongly 

 marked varieties as well as what might be called the typical form. I am now 

 •engaged in studying the earlier authorities with a vie\v to determining which 

 is the type and which the variety. Meanwhile, to avoid confusion, and to 

 aid in the clearing up of diflEiculties, I have defined one variety in my account 

 of the British Tubificidfe, and named it L. lioffmeisteri, var. tenelhdus.~\ 



9. Limnodrilus udekemianus, Clai?. 



Almost as ubiquitous as the last (Mem. de la Soc. de Phj's. de Geneve, 

 xvi (18G2) p. 243). 



10. Limnodrilus claparedianus, Katzel, Zeit. wiss. Zool. 1868, p. 590. 

 Seems not to have been found till the present year. Taken at Kew, 



August 1911. I think it may have been confused at times with one of the 

 other species of Limnodrilus. 



In view of the conflicting statements of the authorities respecting the 

 length of the penis-sheath in the above three species I am subjecting them to 

 careful* measurement. Differences certainly appear to occur ; but when we 

 have eliminated the errors which are due to inaccurate observation and 

 •confusion of species, these differences will either disappear or be reducible to 

 a trustworthy term. 



11. Limnodrilus longus, Bretscher. (Revue Suisse de Zool. vol. ix. (1909) 

 pp. 204-5, figs. 2 & 3.) 



The original description is very brief : '• Intestine begins in segment 5. 

 iSetse in front bundles 5. Penis-sheath straight or slightly bent, over twenty 

 times longer than broad ; reaching through segments 10-12." The note 

 which follows adds nothing to these facts. Southern (9, p. 136) says that " in 

 the Irish specimens the length of the penis-sheath was 21 times the breadth. 



