528 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Weldon’s observations are discussed by him in detail. In concluding 
bis paper, to which we must refer the student, the author points out 
that the advantage of eliminating from the problem of evolution ideas 
which must often, from the nature of the case, rest chiefly upon guess- 
work, need hardly be insisted on. 
Central Nervous System of Shore-Crab.* — Herr A. Bethe, using 
his new modification of Ehrlich’s methylen-blue method (methylen- 
blue-molybdate), has studied the histology of the central nervous system 
of Carcinus msenas. He describes the ventral cord, its neuropil or 
Punktsubstanz, its motor elements, its sensory elements, and its association- 
elements, of which he distinguishes ten types. The brain, with its six 
ganglion masses, the optic nerve with nine types of fibres, the tegumen- 
tary nerve, the antennary nerves I. and II., the oculomotor, and the 
anterior median nerves, are then described. Eight types of association- 
elements connect the parts of the brain, three types connect cells in the 
brain with the ventral cord, and four types connect cells in the ventral 
cord with the brain. But the intricate nature of the investigation 
demands reference to the original and its figures. 
Freshwater Sehizopod from Tasmania.! — Mr. G. M. Thomson 
describes a remarkable and apparently archaic Sehizopod, which he has 
had the good fortune to discover in Tasmania, and of which he has 
already published a short preliminary account. This creature, which 
he now calls Anaspides Tasmania , is regarded by him as being the type 
not only of a new genus, but of a new family of Schizopods. Owing to 
its long isolation it has undergone very profound modification. The 
Anaspididse , of which it is the sole representative, may be defined as a 
family of the Schizopoda in which the carapace is wanting ; the cephalon 
and all the segments of the body distinct ; maxillipeds and succeeding 
seven pairs of limbs uniform in general structure, adapted for walking, 
furnished with external lamellar branchiae ; no egg pouch (?) ; pleopoda 
with well-developed natatory exapodites ; endopodites of first and second 
pleopoda specially modified in the males as copulatory appendages; 
uropoda normal ; auditory organ in the base of the first pair of antennae. 
Nothing is known as to its development. After giving a detailed account 
of its external form and a discussion of its anatomy, Mr. Thomson 
points out that Anaspides is manifestly a Sehizopod shrimp, but its 
greatly generalised characters, and its remarkable habitat in a pool 
near the summit of Mount Wellington, that is at a height of over 4000 feet, 
indicate that it is a survival of a very old type. The most conspicuous 
external features are the want of a carapace and the plate-like character 
of the gills. No other Thoracostracous crustacean is known in which 
the adult has absolutely no trace of a carapace. In general appearance 
the new genus is most like the members of the family Euphausiidae, 
although indeed the points of dissimilarity are numerous enough. The 
alimentary canal shows a much simpler structure than prevails in any 
other described Sehizopod. The liver is unique in its structure, and the 
whole alimentary canal bears a closer resemblance to that of the lower 
Amphipoda than to that of any of the higher forms of Crustacea. This is 
* Arch. f. Mikr. Anat., xliv. (1895) pp. 579-622 (3 figs.). 
t Trans. Linn. Soc., vi. (1895) pp. 285-302 (3 pis.). 
