110 DR. J. STEPHENSON ON TTTR MORPHOLOGY, CLASSIFICATION, 



the name of my former colleague, Prof. Shiv Ram Kashyap of 

 Lahore. 



Diagnosis: — Setpe eight per segment. Male pores on xviii. ; 

 two pairs of prostatic poises, on xvii. and xix. Spermathecal 

 pores two pairs, in 7/8 and 8/9, or on viii. and ix. Gizzard in 

 vi. All septa, present after their commencement. No calciferous 

 glands. Micronephridia; micronephridia relatively large, few 

 in number. Testes and funnels free in x. and xi. 



Distribution :— India (Mahableshwar, S. Rnjputana, Saharan- 

 pur). 



It will be noted that the species extend in a line from the 

 Western Ghats to the Western Himalnyas, the most primitive 

 (at least the one in which the reduction in the number of 

 nephridia has made least progress) being at the southern end, 

 the most modified at the northern. 



The relationships of the genera of Octocha^tinaD may be set 

 forth in the accompanj'ing tree : — 



"Original Acanthodviliiie." 



(Sowascolex ?). 

 Octochestus. HoplochceteUa. Eamiella. 



BinodrUns. mitjtphneus. I muUcliogaster. 



T^ri/thrandrilns. 



(On the question of the inclusion of Eoioascolex in the ancestral 

 line of the Octochsetina? see (8), and the references there given. 

 On the inclusion of ffoplochcetella and Erythrceoclrilus in the 

 Octochfetince see (10).) 



Probably no genealogical tree expresses relationships with 

 exactitude: every genus is strictly speaking at the end of a 

 short side line. Thus Ramiella probably comes off the main 

 stem shortly above the position of Sowascolex ; the original 

 meganephridium seems to have broken up in a different way in 

 these two genera — in Houmscolex to have become one still fairly 

 lai-ge and a number of minute nephridia, in FamieUa to have 

 dissolved into a few moderate- sized organs. 



The Derivation of the genus Dichogaster. 



There remains the question of the origin of the genus 

 Dichogaster. In 1903 and 1909 Michaelsen regarded it as 

 derived from Etbdichogaster ; while in 1910 he states that 

 morphologically it is best derived from Eudichogaster, though 

 o-eoo-raphically it would appear easier to derive it from Trigaster; 

 the o-eographical argument is, however, not by any means 

 absolutely cogent — there is nothing in the facts essentially 

 opposed to the derivation from Eudichog aster. 



To this view of the origin of Dichogaster I cannot agree. In 



