ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 299 



various stages of their development, arrive at maturity in about two 

 weeks, and proceed to lay more eggs. The male is somewhat smaller 

 than the female, which measures ^ to ^ in., and each foot of the 

 first three pairs of legs of the male is furnished with a sucker-disc, 

 which in the case of the female is replaced on the third pair of feet by 

 long hairs. The usually effective cure is to make the sheep swim in a 

 bath of "dip," i.e. some preparation of white arsenic, carbolic acid, 

 tobacco-juice, sulphur, &c. ; but prevention is better than cure. 



f. Crustacea. 



Integumentary Sense-Organs of Deep-Sea Decapods.* — E. Kotte 

 has made a detailed study of the appendages of Plesionilca cottei, and 

 of its tactile and gustatory organs. He also discusses in particular the 

 sensory tufts on the thoracic appendages of Nematocarcinns undulatipes. 

 His general conclusions are the following : — (1) All the integumentary 

 organs are sensitive ; (2) they include a terminal strand, the distal 

 process of a subjacent group of sensory cells, which is proximally con- 

 nected with a nerve ; (3) while in the lower Crustaceans only a few 

 sensory cells are concerned with the innervation of a seta, there is a 

 large number for each seta in the Decapods, especially in the abyssal 

 forms ; (4) in the course of the nerve-fibres which innervate the struc- 

 tures regarded as gustatory or olfactory, two cells are interpolated, — a 

 peripheral ganglion-cell and a sensory cell. 



Excretion in Cirripedia.t — L. Bruntz has used the injection 

 method in studying the excretory organs in Lepas anatifera, Polliapes 

 cornucopia, Balanus tintinnabulum, and Sacculina carcini. In the three 

 first he distinguishes three excretory organs : — (1) the maxillary kidney 

 which eliminates injected carrnin ; (2) a closed cephalic organ, a lenti- 

 cular body situated where the mantle is attached to the body ; and 

 (3) the hepatic gland. In Sacculina the only excretion detected was by 

 osmosis over the whole surface of the absorptive roots. 



Ventral Nerve-Cord of Crayfish4 — B. Halpern describes the 

 minute structure of the enveloping and supporting tissue of the ventral 

 nerve-cord of Astacus fluviatilis. There are two sheaths, — the "peri- 

 neurium " and the " endoneurium." The perineurium consists of con- 

 nective-tissue strands and owes its firmness to a layer of elastic fibres. 

 It forms the originally double septum between the connectives. 



The endoneurium differs from the perineurium in structure and 

 origin. It functions as the immediate sheath and support of the 

 nervous substance. Each axis-cylinder is surrounded by two sheaths, — 

 the internal one being a delicate membrane in which longitudinal fibrils 

 are imbedded. The ganglia show (1) small cells with a double-con- 

 toured membane, (2) " colossal " cells without a homogeneous membrane, 

 but with a plexus of fibrils at the periphery, and (3) transition types 

 between these. 



* Zool. Jahrb., xvii. (1903) pp. 619-58 (5 pis.). 



t Comptes Rendus, cxxxv. (1902) pp. 987-8. 



X Arbeit. Zool. Inst. Univ. Wien, xiv. (1903) pp. 423-42 (12 figs.). 



