336 MR. ROBERT GURNET ON 



cilia with the specimens described hy Stingelin (1904) from Java 

 and Honoluki, except that here the chxws have no cilia. But in 

 my specimens the shell is distinctly striated, but vi'ithout reticu- 

 lations, thus approaching more nearly to Richard's description. 



I have already (1911) given reasons foi' regarding A. davidi 

 sa\d A . punctata Dadny as varieties oi A. diaphana King, but I 

 am inclined to think that, though I still believe the three species 

 to form a gradational series, yet it is perhaps more convenient 

 and less cumbrous to leave the thi-ee names to define the three 

 varieties. 



Alonella karua King. 

 Peradeniya and Anuradhpura, 



Alonella excisa Fischer. 

 Peradeniya pond. 



Chydorus parvus Daday. (PI. I. figs. 2, 3.) 



Peradeniya pond and Priest's Well ; Kandy ; Anuradlipura. 



In 1898 Daday described, imder the name of C. sj^hrericus var. 

 parvus, a Chydorus from Colombo Lake, differing cliiefjy from 

 C. sphoiricus in the form of the upper lip (fig. 2), and I have 

 little hesitation in referring to this species a Ghydoras which is 

 common in some of Mr. Smith's collections. These specimens, 

 which vary from -28 to '35 mm. in length, are nearly globidar in 

 shape and usually of an opaque golden-yellow colour. In the 

 form of the upper lip and of the post-abdomen (fig. 3) they agree 

 very closely with Daday's description, but they differ in the fact 

 that I have been unaljle to detect with certainty any sculpture 

 on the shell, whereas Daday's species shows strong reticulation. 



Chydorus barroisi Richard. (PI. I. figs. 4, 5.) 



Peradeniya pond ; Anuradhpvira. 



My specimens unite in a very perplexing way the characters 

 of C. barroisi and C. poppei Richard. All my specimens agree in 

 having the upper lip strongly serrated and in the arrangement 

 of spines on the post-abdomen (fig. 5), and nearly all have the 

 shell-valves smooth. The majority have also a tooth at the 

 posterior ventral angle of the shell (fig. 4) and an additional 

 minute spine at the base of the caudal claws, but I have also 

 seen specimens which lack the one or the other. In the structure 

 of the ]30st-abdomen they agree much more closely with C. po]jpei 

 than with C. barroisi. C. hybridus Daday unites in the same 

 way the characters of the two species, and it seems to me that 

 the three are not, in fact, specifically distinguishable. C. poppei 

 has been recorded only from South America and from the 

 Southern United States, but 0. barroisi occurs in Syria, Ceylon, 

 various parts of Malaysia, Xew Zealand, East Africa, and South 

 America. Stingelin (1913) also expresses the opinion that the 

 three above-named species should probably be united into one. . 



