61 
vagina, and the presence of frontal eyes. The two last mentioned 
are, however, not valid in all cases. As far as I know, only Pr. 
mvaense Yeri & Kaburaki 1918 of the described Prosthiostomum- 
species has eyes between the cerebral and marginal eye clusters. 
As regards vagina, see above. Enchiridium is the only Prosthi- 
ostomid that has eyes along the entire margin of the body. The 
new genus, which is placed in the immediate neighbourbood of 
Prosihiostomum, is diagnosed as follows: 
Prosthiostomids with marginal eyes only in the 
anterior region of the body and frontal eyes. No gut 
branch above the pharyngeal pocket. The two separate 
accessory vesicles of the male apparatus small, club- 
shaped, with short efferent duets forming the direct 
continuation of the vesicle. The proximal part of the 
vagina directed forwards. Sucker at a decided distance 
from the female gonopore and situated near the post- 
erior margin of the body. 
One species from Panama, living associated with Pagurids. 
Emprosthopharynx opisthoporus Bock 1913. 
(Plate II a. Fig. 5—7.) 
Locality: Panama, Taboguilla. In the houses of the large Pa- 
gurid Petrochirus californiensis Bouerez. 
Sandbottom. 
Panama, Taboga. Also with the same Pagurid species. 
Depth ca. 9 m. 
Material: In the collection there are in all not less than 8 spe- 
cimens, three of them taken Nov. 27th and the others 
Dec. 7th, 1915, at the last mentioned locality. 
It is of interest to receive more material of this species, as the 
original description (Bock 1913) was founded on a single specimen. 
This was obtained by the Swedish Eugenie Expedition visiting 
the Galapagos Islands in 1852. Its relationship to other Aco- 
tyleans is not yet clear. I may here mention that a second spe¬ 
cies, an extremely minute one, was collected by me in the Gilbert 
Islands in 1917. The presence of eyes arranged parallelly in respect 
vto the body margin made me rank the genus among the 
