Norwegian Solenogastres. 23 
which was established by Heatu in 1911; both come from South 
California, deep water (840—2500 m.). Their characteristic uni- 
serial radula, unique in the Neomeniidae, and their cuticular 
papillae as well as the structure of the pharynx and the gills, are 
so singular that these animals are easily distinguished from all 
other Solenogastres. The present species is quite distinct, differ- 
ing from the two others in possessing a dorsal keel (fig. 27) and 
having a less number of gills (fig. 34). The shape of the gills 
in this genus is aberrant from that of other Neomeniidae, in as 
much as each gill constitutes a fold projecting perpendicularly 
from the cloacal wall and is in its turn folded, carrying a furrow 
along its external margin; all the gill folds, moreover, are con- 
nected with each other at their outer edges, which project at the 
sides of the furrows, as shown in fig. 5, pl. 5, by Heatn, 1911. 
Whereas in Neomenia the gills are constituted of isolated folds 
radiating from the interior of the cloaca towards its aperture, 
those of Alexandromenia show quite a different type, which is 
deducible from a circular fold rising from the wall round the 
aperture and secondarily wrinkled by furrows alternating on its 
external and internal suriace. 
The shape of the radula teeth (fig. 32) of this species resemb- 
les most closely that of A. valida (cf. Heatu pl. 34, fig. 14), 
but there are a larger number of denticles in the concave margin 
of the present form, and the rhachian denticle is the smallest and 
composed of two parts. A further difference exists in the dorsal 
coecum of the intestine, which penetrates far in front, beyond 
the brain (fig. 33). There may perhaps also be differences in the 
Structure of the pharynx, the walls of which seem to be less 
glandular here than in the other species; as I have made no 
sections, this question must be left undecided. Apart from the 
differences mentioned there is considerable agreement in essential 
characters, so that the inclusion of the new species in the genus 
Alexandromenia is quite justified: the hypodermic papillae, the 
radula, the coelomoducts, the ventral folds and the gills show 
the generic type, and to these facts may be added the powerful 
development of the intestinal wall. 
A transverse section through the median part of the body 
(fig. 28) exhibits the following features of organization: Beneath 
the hypodermis there appears a circular muscle layer, and within 
it one consisting of crossing fibres. Inside the latter follows a 
