Genera Trigaster and Benliamia. 415 
agrees with Trigaster Lanhesteri , but differs in several of the 
characteristic features of the latter, one being the possession 
of two gizzards and another the extent of the clitellum. Dr. 
Michaelsen, however, suggested the suppression of the name 
Trigaster in favour of Benliamia , on the ground that the 
former generic name no longer holds good for his new species 
on account of its significance. 
In my recent article, u An Attempt to Classify Earth- 
worms ” (Quart. Journ. Micr. Sci. xxxii.), I have included 
his species under the older name Trigaster ; this I did 
believing that, although the name had no longer a literal 
significance for the new species, I was justified in retaining 
the prior name. Dr. Michaelsen has published descriptions 
of other species of the same genus, and after communication 
with him and with Dr. Rosa, of Turin, and a careful perusal 
of his papers, I am led to regard the species of Benhamia 
as distinct from Trigaster . The two genera are not 
synonymous, as would appear from his article, but are 
distinct though very closely allied forms ; and perhaps they 
should both be regarded as subgenera of Acanthodrilus . At 
present, however, I would consider them as distinct. 
The following characters are common to the three genera, 
together with Deinodrilus (Beddard) : — 
(1) Nephridia in form of a network. 
(2) Two pairs of coiled cylindrical prostates in somites 
xvii. and xix. 
(3) Two pairs of spermathecae. 
Deinodrilus differs from the rest in possessing twelve seta 3 
per somite and in its short clitellum (xiv. to xvi.). 
Acanthodrilus has a single gizzard and behind it paired 
calciferous glands. 
The anterior nephridia form a compact mass or pepto-neph 
communicating (? always) with the pharynx. 
The spermathecse lie in somites vii. and viii. 
The two sperm-ducts of each side are separate till near the 
sperm-pore. 
Trigaster : — 
1. The clitellum is extremely long, occupying somites xiii. 
to xl. 
2. There are three separate gizzards, in somites vii., viii., 
and ix. 
3. There are no calciferous glands. 
