416 On the Genera Trigaster and Benhamia. 
4. The two pairs of spermathecae lie in viii. and ix., are 
globular, have no appendix or swellings or diver- 
ticula near the external apertures, which are placed 
posteriorly, i. e . between viii./ix. and ix./x. 
5. No penial setae. 
6. No dorsal pores. 
Benhamia : — 
1. The clitellum occupies at most eight somites, varying, 
however, in extent and limits (xiii. to xix. or xiv. 
to xxi.). 
2. There are only two gizzards. 
3. Calciferous glands are present. 
4. The spermathecae are rather ovoid than globular and 
have appendices or diverticula to their narrowed 
ducts, which open externally on the anterior boun- 
daries of their somites, viz. vii./viii. and viii./ix. 
5. Penial setae in special sacs are present in relation to the 
prostate. 
6. Dorsal pores are present, at any rate in some of the 
species. 
Both genera, however, agree in having all the eight setae 
in each somite close together on the ventral surface, in having 
a pit or fossa, at the bottom of which the prostates and spermi- 
ducal pores open externally, and in these two characters they 
differ from Acantliodrilus . 
The genus Trigaster includes at present only one species, 
T . Lankesteriy Benham, 1886, from St. Thomas, West 
Indies. 
The genus Benhamia includes the following species, all 
being from West Africa, with the exception of the last, 
the locality of which is unknown, and is merely a matter of 
speculation : — 
1. B. rosea , Michaelsen, 1889. 
2. B . Stuhlmanniy Michaelsen, 1890. 
3. B. affinisy Michaelsen, 1890. 
4. B. Schlegeliiy Horst, 1884. 
5. B. Biittikoferiy Horst, 1884. 
6. B. Beddardi, Horst, 1888. 
7. B . scioanay Rosa, 1888. 
8. B. Godeffroyiy Michaelsen, 1890. 
