40 THREE CRUISES OF THE “BLAKE.” 
Acanthodromia, which recalls from the shape of its carapace 
fossil crustacea characteristic of the secondary formation, and 
Dicranodromia, are peculiar new genera of Dromide inhabiting 
depths of 100 to 200 fathoms; while Homolopsis, with eyes 
nearly atrophied, 1s, like Cymonomus just mentioned, a Medi- 
terranean genus which has been found by the “ Blake" in the 
depths of the Caribbean. Homalodromia, a genus of the fam- 
ily of Homolid:e, is in some respects intermediate between it 
and the Dromid:e, two families thus far most distinct, and occurs 
in greater depths, from 300 to 600 fathoms. 
Among the hermit-crabs (Paguroidea) the species thus far 
known were very similar, the head and claws alone being hard 
and calcareous, while the soft terminal parts of the abdomen 
are in the littoral species tucked away for protection into all 
sorts of bodies, such as shells and 
the like. It must be most difficult 
often for the deep-water species to 
find appropriate hiding-places, and 
it is not astonishing that the 
dredgings of the “Blake” have 
brought to light a number of re- 
markable new forms, whose char- 
acteristies unite them with the 
Macrura ; as, for instance, Pylo- 
cheles Agassizii, which has a per- 
fectly symmetrical tail. It lives in 
cavities excavated in fragments of 
stone formed of agglutinated sand. 
It entirely fills the cavity, closing 
the opening with the claws, which 
form a perfect operculum. Xylo- 
pagurus rectus (Fig. 233), a slen- 
der hermit-crab, inhabits tubes ex- 
cavated in bits of wood (Fig. 234) 
Fig. 233. Fig. 234. 
Xylopagurus rectus. 1, 
(Milne-Edwards.) or the hollow stems of plants open 
previously known only from the North- the West Indian region were discovered 
ern and Southern oceans. On the other off the New England coast. 
hand, species previously known only from 
