382 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Asellid, found by A. Vire in a Cevennes well. The body is very 
narrow ; the head is closely united to the first pereial segment ; the 
first pair of antennas are shorter than the second ; there are olfactory 
hairs, but no eyes ; on the segments 2-7 of the pereion, the coxal parts 
are very small ; the first pair of pereiopods have elongated protopodites ; 
the succeeding limbs are delicate ; the pleon has the first three segments 
free and much developed ; the pleotelson is oblong and elongated ; the 
uropods are greatly developed. 
It is premature to say that these are archaic forms, relics of a 
Tertiary marine fauna ; but there is no doubt as to their interest. 
Sense-Organs of Subterranean Crustaceans.* — M. Armand Vire has 
previously noticed in regard to cave-animals that, as the eye disappears, 
other sense-organs become hypertrophied and acquire a new delicacy. 
He confirms this in reference to the two Isopods described by Dollfus. 
In Sjphseromides Baymondi there are remarkable tactile hairs ; some 
are straight, rigid, and unbranched ; others, especially on the antennae 
and limbs, are slightly jointed at the base, and, about half-way up, swell 
and give off minute secondary hairs of great mobility and delicacy. The 
author does not give any histological or other proof that the hairs are 
tactile ; but one must remember the preciousness of the specimen. The 
olfactory organs were crushed. 
In Stenasellus Virei the tactile hairs resemble those above mentioned. 
The olfactory organs consist of flattened lamellae supported on a stalk 
which is articulated to the end of each segment of the antennule. A very 
interesting series is noted. In Asellus aquations, from the brooks round 
Paris, the organ is hardly half the length of one of the segments of the 
antenna ; in the same species living in darkness in the subterranean 
water-conduits of the city it is almost as long as a segment ; in those 
from the catacombs of Paris it exceeds the length of a segment ; in 
Stenasellus it is more than one-and-a-half times the length of a segment. 
The reverse is true of the eye : it is black and well-developed in the 
Asellus of the brooks ; it is paler in those from the conduits ; it is re- 
presented only by red points in those from the catacombs ; in Stenasellus 
it is quite absent. The series confirms “ Geoffroy Saint-Hilaire’s law of 
the balance of organs, and Darwin’s theories of the influence of environ- 
ment.” 
Eye of Corycseus.j* — Dr. A. Steuer makes a preliminary communica- 
tion as to the structure and function of the eye in Corycseus anglicu & 
Lubbock, a Copepod related to Copilia which Exner investigated. The 
frontal margin shows the usual large lens, connected by a conical tube 
(eye-sheath), with the internal pigment-rod, which bears a Secretkugel 
( Secretlinse ) at its cup-shaped anterior end. As in other Corycseidse, 
the frontal lens consists of two parts, and on the inner side there is a 
non-cellular part hitherto overlooked, The eye-sheath is a complete, 
finely fibrous tube, containing only blood. At the end of the pigment- 
rod are seen the optic cells and the cylindrical optic rods. At the 
upper part of the pigment-rod and to the ventral side, lies the so- 
* Comptes Reiidus, cxxv. (1897) pp. 131-2. 
f Zool. Anzeig., xx. (1897) pp. 229-32. 
