49 
Euprosthiostomum adhaerens n. g. n. sp. 
(Plate II a, Figs. 1—4.) 
Locality: One specimen collected at a depth of 13 fathoms at 
Taboguilla Island, Gulf of Panama, November 27, 1915. 
Two specimens collected at a depth of 5 fathoms on 
Taboga Island, Gulf of Panama, December 7, 1915. 
Habitus: The body of the preserved spe¬ 
cimens is somewhat elongated and of nearly 
even breadlh, with its anterior and posterior 
ends rounded (text-fig. 14). Although decidedly 
contracted, the largest specimen (from Taboga) 
measures øVs mm. in length and SVs mm. in 
breadth. The type specimen from Taboguilla, 
which is reproduced on Plate II a, Fig. 1, is, 
as can be seen in the photograph, also very 
contracted. Therefore, the living animals of this 
species must, when fully extended, have a length 
that is 4 or 5 times its breadth. Particularly 
noteworthy is the wide caudal end, which is 
not drawn out and tapered, as in the genus 
Prosthiostomum, but rounded, a shape that must 
be connected with the location of the sucker. 
None of the specimens show any pattern, but 
the dorsal epithelium has retained an even 
slightly brownish colour. 
Measurements: The specimen on which 
the following description is based, and of which 
I have a complete series of sections, measures 
in length 5 mm. and in breadth barely 2 mm. The mouth is 
immediately back of the brain, on a level with the posterior line 
of the brain; consequently, at the end of the first seventh of the 
body. The pharynx is one-fourth the length of the body (Plate II a, 
Fig. 1). The marked caudal location of the very large, oval sucker 
(Plate II a, Fig. 2, s) is the best characteristic, as until now a similar 
location is not known for any other Prosthiostomid. The distance 
from the posterior edge of the sucker to the caudal limit of the 
body is not even the length of the sucker. The sucker is V 12 the 
length of the preserved specimen. As the posterior part is hardly 
Vidensk. Medd. fra Dansk naturh. Foren. Bd. 79. 4 
Text fig. 14. Euprosthio 
stomum adhaerens n. 
g. n. sp. The body 
from the ventral side. 
15 X. m, mouth; ph, 
pharynx; sf, sense 
fiirrow; s, sucker. 
