338 SUMMARY OF CURRENT RESEARCHES RELATING TO 



epimera, on each side, in a sieve-like aperture. In the tail, the 

 i-educed segments do not show the " sieves," the glands undergoing a 

 6ort of concentration, and all opening together in a slit pierced with 

 holes arranged in linear series. This slit is on the external side of 

 the external urostyle. 



Each of these glands consists of cellular elements of comparatively 

 gigantic dimensions, some of them measuring • 2 mm. Each is com- 

 posed of a knobbed, indented, lobate body, always enclosing two 

 large, symmetrical, granular nuclei, close to one another. Each 

 nucleus contains a nucleolus, also very granular. The nuclei are 

 coloured red by carmine, and blue by iodized serum. Between them 

 winds a sort of vestibule, from which issues a canal, filled with the 

 secreted substance. The canals do not anastomose, but end separately 

 in one of the sieve-like apertures, or in the slit of the urostyles. 



This arrangement is found in the greater part of the terrestrial 

 Isopoda, Porcellio scaber, Oniscus murarius, Armadillo, and Ligia. 

 Porcellio pictus has only the caudal glands. It is not found in any 

 aquatic Isopod, nor in Ligia oceanica, nor in Anilocra, Idoteidce, or 

 Asellus aquaticus. 



Bopyridae.* — E. Walz deals in order with the different parts of 

 the organization of these parasitic Crustacea ; the cuticle of the male 

 is said to be thicker than that of the female ; the larval stages do not 

 differ from one another in any important particulars ; the changes 

 early undergone by the mouth-organs are noted ; later on, the oral 

 cone calls to mind the suctorial proboscis of some Siphonostomata. 

 On the inner side of the base of the first five pair of legs are deve- 

 loped the brood-lamellfe, which acquire their full size when the 

 female reaches maturity ; they are always membranous, and their 

 chitinous cuticle is produced, as a rule, into short denticles. Vary- 

 ing a good deal in form, they determine that of the brood-pouch. The 

 gills are thin, lobate, rarely tubular appendages ; they always decrease 

 in size from before backwards, and are, as a rule, better developed in 

 the female than in the male ; in the latter, indeed, they are often 

 nothing more than small protuberances on the abdomen which dis- 

 appear with age. Each lamella consists of two folds with a very 

 narrow intermediate space ; from one wall there pass to the other 

 supporting bars, which have a homogeneous clear appearance and are 

 to be regarded as cuticular structures. The digestive apparatus 

 ■exhibits special characters, in correspondence with the parasitic habits 

 of its possessors ; the fore-gut is first enlarged and then narrowed to a 

 itube ; it leads into a wider portion, and the whole is so arranged as to 

 act as a suctorial jiump. The fore-stomach is enlarged into a crop, 

 •and the inner wall of some forms is provided with a number of 

 processes, by means of which there is a considerable increase of sur- 

 face ; but this peculiarly arranged crop is, it is curious to note, found 

 ■only in the female and not in the male, where the corresponding 

 jegion forms but a very slight enlargement. The mid-gut likewise 

 is much smaller and narrower in the male than in the female. The 

 salivary glands which have been described by Cornalia and rauccri, 



* Claus' ArbLitcn, iv. (1882) pp. 125-200 (4 pis.). 



