32(3 SUMMARY OF CURRENT RESEARCHES RELATING TO 
Phytoptidae.* — Prof. G. Canestrini gives an account of this family. 
This is a shortened statement of their general characters : — The body is 
divided into an anterior portion (“ cephalothorax ”) with limbs, and a 
posterior portion (abdomen) without limbs; there are free, short, simple, 
three-jointed palps, aciculate mandibles, a proboscis adapted for suction ; 
there is an absence of tracheae, special circulatory organs, and eyes ; 
the integument is delicate, the shape vermiform, and there are two pairs 
of five-jointed limbs ; the sexes are separate and not markedly di- 
morphic, the gonads are unpaired ; in post-embryonic development there 
are two moults and two immature forms. An account is given of the 
various ways in which these parasites affect plants, producing galls and 
other deformities, sucking leaves and fruits, and so on. The author 
gives diagnoses of the genera : — Phytoptus , Cecidophyes , Phyllocoptes , 
Tegonotus, and Oxypleurites, a detailed description of seventy species, and 
a list of the plants which are attacked. 
Striped Harvest-Spider. | — Mr. C. M. Weed makes this PJialangium 
the text of an interesting study in variation. Say, in 1821, described 
P. vittatam and P. dorsatum. From the examination of several 
hundreds of specimens the author concludes that we have to do with a 
single very variable species, in which natural selection has increased 
the size of the body and the length of the legs to the southward (of the 
United States) and shortened them in the north. 
Affinities and Origin of the Tardigrada.J — Prof. J. von Kennel 
accepts and starts from Plate’s view that the Tardigrada are related to 
the tracheate Arthropoda, but he cannot assent to the doctrine that 
they are lower than Peripatus. He points out, on the other hand, the 
great resemblances between Tardigrades and greatly modified tracheate 
larvaB, and urges that the differences that there are between them are 
due to the advanced degeneration of the “ Bear-animalcules ” and, pos- 
sibly, to neomorphs. In considering the embryology of Tardigrades we 
must bear in mind that it may have undergone great secondary modifica- 
tions. 
e. Crustacea. 
Nervous System of Heart of Crab.§ — MM. F. Jolyet and H. Vial- 
lanes have studied the physiology of the acceleration and inhibition of 
the heart of the Crab. In a general way strong stimuli slow the 
cardiac rhythm, while slight and prolonged stimuli accelerate it. 
Both accelerating and inhibiting cardiac centres are confined to the 
suboesophageal mass. The authors have not been able to find in the 
Crab the cardiac nerve which has long been known in macrourous 
Crustacea, and which has been regarded as the only accelerator of the 
heart. 
Nephridia and Body-cavity of Larva of Palaemonetes varians.|| 
Mr. E. J. Allen has a preliminary communication on the development 
of this Crustacean ; his investigations lead him to suggest that both 
* Atti Soc. Ven.-Trent. Sci. Nat., 1893, pp. 49-98 (16 pis.). 
t Amer. Naturalist, xxvi. (1892) pp. 999-1008 (l pi ). 
t SB. Nat. Ges. Univ. Dorpat, ix. (1892) pp. 504-12. See Ann. and Mag. Nat. 
Hist., xi. (1893) pp. 197-204. § Ann. Sci. Nat., xiv. (1893) pp. 387-404. 
|| Proc. Roy. Soc., lii. (1893) pp. 338-42. 
