NOTES ON ACANTHODRILOID EARTHWORMS. 307 
These pores in Perionyx are, relatively to the chete, in 
about the same position as in Plagiocheta, but the male 
pores and oviducal pores are in depressions. 
The position of the clitellum and its appearance are more 
Perichetous than Acanthodriloid. 
With Perichxta Stuarti it is in agreement in the position 
of the genital pores and in the character of the prostates ; but 
this species has no appendix to its spermatheca, and differs 
from Plagiocheta in other points. 
The alternation of the nephridiopores calls to mind 
Perionyx saltans of Bourne, Acanthodrilus nove- 
zealandiz, and other species, and Plutellus of Perrier; 
but with none of these does it agree in the essential generic 
characters. 
The genus differs considerably in its internal anatomy from 
Pericheta, viz. in the character of the nephridium, in the 
shape of the prostates, in the position of these, and the posses- 
sion of two pairs of them; in the presence of calciferous 
glands, in the absence of gizzard and of intestinal ceca ; 
in the arrangement of sperm-sacs, in the shape of the 
ovary, &c.! 
With Acanthodrilus it agrees in the position of the 
male pores and in the character of the prostates, and with 
some species in the arrangement of the nephridia, and in the 
presence of sacs containing penial chete. But Plagiocheta 
differs from Acanthodrilus, and its allies Trigaster, 
Benhamia, and Deinodrilus, in the form of the clitel- 
lum, in the arrangement of the chet, in the absence of a 
gizzard (cf., however, Ac. Georgianus, Mich.). 
Mr. Beddard has pointed out that the interesting genus 
Deinodrilus presents a somewhat similar mixture of Peri- 
chetoid and Acanthodriloid characters; and it seems to 
me that Plagiocheta more closely resembles in certain points 
each of these genera. In its locomotor organs it is closely 
1 P, intermedia, Beddard, and P. Bakeri, Fletcher, however, possess 
two pairs of prostates, which are cylindrical or “acanthodriloid” in the 
former species. 
