538 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
structure and their habits, their means of offence and defence, and their 
modifications by the environment. 
Mouth-Parts of Mites.* — A. Brucker describes in Trombidion, &c. 
— (1) a rostrum hearing the chelicerae, and;(2) a pharyngeal proboscis 
fused to the pedipalps. The same is true of the Gamasidse, but the ros- 
trum coalesces with the apparatus formed by the proboscis and pedipalps, 
and forms a complete tube within which the chelicerae are movable. 
Spider and Piteher-Plant.t — Mr. K. I. Pocock gives an account of 
an interesting observation by Mr. A. Everett. It concerns Misumena 
nepenthicola, one of the Thomisidee, which invariably takes up its abode 
in the pitcher of a North Bornean (Labuan) Nepenthes , probably N. phyll - 
amphora. The web is a thin carpet spread over a small portion of the 
conductive area, and enables the spider to maintain its hold on the 
slippery surface. Here the spider lives and rears its young, no doubt 
feeding upon the insects which the Nepenthes attracts. The peculiar 
habitat doubtless helps the spider to escape the attacks of the mason 
wasps which are so fatal to spiders. Moreover, when the pitcher is torn 
open, the spiders plunge into the liquid and retreat to the very base 
among the debris of captured insects. The adoption of water as a city 
of refuge is known in some spiders, such as Dolomedes, Thalassius , some 
species of Lycosidge, and Araneus ( Epeira ) cornatus, but it does not seem 
to have been previously recorded of any member of the Thomisidae. It 
appears to be a new instinct acquired by the species in connection with 
its peculiar habitat. 
e. Crustacea. 
Poecilogony in Alpheus minor.J — H. Coutiere notes that the larval 
development in this species may be abridged or lengthened according to 
the individual environment. In specimens from the Antilles the larval 
development is much abbreviated ; in those from the Gulf of California 
the newly hatched larvae are much less advanced. This should be com- 
pared with the observations of Boas on Palsemonetes varians in fresh 
water and in the sea. 
New Parasitic Copepods on Fishes.§ — Staff-Surgeon P. W. Bassett- 
Smith adds considerably to his previous discoveries. He describes ten 
new species, and establishes a new genus Pseudoclavella, near Oken’s 
Clavella in the family Dichelesthina. He directs attention to the con- 
stancy with which particular parasites are found on particular hosts. 
Parastacus.|| — Dr. E. Lonnberg communicates some welcome bio- 
logical and anatomical notes on Parastacus Hassleri Faxon, which has 
long been a puzzle to zoologists. Sexual dimorphism is well marked, 
and the animals are completely dioecious, but every individual of both 
sexes is provided with two pairs of genital ducts, two anterior ones lead- 
ing to the “ orifices ” on the coxopodites of the third pair of legs, and 
two posterior ones on the fifth pair. In reality, the posterior pair in the 
female are too narrow to allow the passage of an egg, and the “ orifices ” 
* Comptes Rendus, cxxvi. (1898) pp. 1821-3. f Nature, lviii. (1898) pp. 274-5. 
X Comptes Rendus, cxxvi. (1898) pp. 1430-2. 
§ Ann. Nat. Hist., ii. (1898) pp. 77-103 (4 pis.). 
|| Zool. Anzeig., xxi. (1898) pp. 334-5, 345-52 (3 figs.). 
