ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 643 



and decurved. The brain is in the prothorax in old larvae. The stomach 

 is closed in the larva. Three Malpighian tubules are attached at both 

 ends, and two are attached at one end, — all metamorphosed iuto silk- 

 glands in their middle portion. The small intestine is modified as an 

 outlet for the silk secretion. The spinneret is formed from the terminal 

 part of the alimentary canal. 



A completer account than has hitherto appeared is given of the hite 

 stages of wing development, and the variations in the venation of fifty 

 wings are tabulated. 



So-called Microthorax of Insects. * — F. Silvestri concludes from a 

 study of Japyx, Campodea, &c. that the " microthorax " or " Nachen- 

 segment " distinguished by Yerhoeff, is nothing more than a part of the 

 labial segment. 



The segment which in Chilopods bears the maxillipedes is homo- 

 logous with the prothorax of insects. Verhoeff's " microthorax," if it be 

 regarded as part of the labial segment, is homologous with the first limb- 

 less segment of Diplopoda, — the neck-shield with its sternum. 



Sense-Hairs of Lepidopterous LarvEe.f — W. A. Hilton finds that 

 Lepidopterous larvse are clothed with hollow hairs, each of which is 

 supplied by a bipolar nerve-cell, a process of which penetrates a short 

 distance into the hair and probably terminates before reaching the tip. 

 In most species all body-hairs are sensory; large hairs are supplied by 

 large bipolar nerve-cells, and small ones by smaller bipolar cells. 



Under the hypodermis of caterpillars there is a system of multipolar 

 cells more or less intimately connected with nerve-cells and fibres, which 

 (a) stain lighter than the larger nerves, and (b) are closer to the hypo- 

 dermis than the other cells and fibres. Nerves from bipolar sensory 

 nerve-cells go to the central nervous system, run to the ganglia, leaving 

 at once to follow on the outside of the connectives towards the head, 

 furming a well-marked sensory tract. Motor nerves — going to muscles — 

 seem to come directly from the central cell areas of the ganglia. Almost 

 the only sensory termination of nerves on tbe body of insects is by means 

 of the hairs. 



Culicidse of Algiers. $ — H.Souliehas made a number of observations 

 on the CulicidaB of Algiers, which show that malarial regions are rich in 

 Anopheles, and that the genus Culex is not an agent in diffusing the 



disease. 



Oogenesis in Hydrophilus piceus.§ — Fr. Megusar finds that the 

 ovarian tubes are not terminally united to the heart region by a common 

 strand, as is generally supposed. The terminations of the tubes are 

 connected with the diverticula of branched glands which stretch towards 

 the pericardial region and form there a funnel-like structure suggestive 

 of the funnel of a nephridium. From this structure numerous raniifi- 

 cotions and diverticula proceed, and it is here that the germ-cells are 

 primarily formed. The seat of the formation of the ova is not really 

 in the blind ends of the ovarian tubules, nor in their prolongations— 



* Zool. Anzeig., xxv. (1002) pn. 619-20. 

 t Amer. Nat., xxxvi. (1902) pp. 561-78 (23 figs.). 

 % Comptes Kendus, cxxxv. (1902) pp. 118-20. 

 § Zool. Anzeig.. xxv. (1902) pp. 607-10. 



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