ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 507 



separate cells begin to be distinguished from their neighbours ; many 

 of them increase in size by the growth of their peripheral portion, 

 and the internal contents of these do not therefore become altered in 

 character. Others develope within themselves fatty bodies. Under 

 the influence of the growing ova the paired portions of the ovarian 

 tubes increase greatly in diameter, and soon after this the eggs make 

 their way into the maternal cavity, where they pass through the 

 stages of development prior to the Nauplius condition. The dorsal 

 folds are chiefly formed of a connective tissue, which consists largely 

 of membranous elements and partly of spindle-shaped fibres, which 

 may be regarded as muscle-cells ; in addition to these there are 

 rounded fibres, which extend from one surface to the other. Eounded 

 or ellipsoidal bodies are to be found lying in the meshes of the 

 tissue, filled by a very regularly arranged polyhedral meshwork 

 of very delicate membranes. A number of fatty cords traverse 

 the appendage in a radial manner ; these are processes of the fat-body 

 which is so frequently found in parasitic Crustacea and are here 

 particularly well developed. The investing membrane is a continua- 

 tion of the general chitinous covering of the body, though it is here 

 more delicate than in other regions. As there is in all essential 

 points the very closest agreement between the structure of these folds 

 and that of the other parts of the body, it would be better to speak of 

 them as processes of the body-cavity, than as dermal folds. The 

 specially modified portion which serves as a brood-pouch has its 

 internal lamella formed by a specially thick chitinous membrane, 

 and is at first so folded as to allow of the increase in size of the cavity 

 which becomes necessary later on. 



Some of the habits of these forms are treated of in detail, and it 

 is pointed out that the first copulation commences before the final 

 ecdysis of the female, but the attachment of the spermatophores only 

 becomes completed after the ecdysis ; in this action of the male, the 

 appendages, and specially the fourth or fifth pair of feet, take part. 

 Various males may fertilize the same female who remains completely 

 passive during the whole act. The reason of this apparently prema- 

 ture copulation is considered, and the suggestion is made that it 

 is an arrangement derived from an earlier condition in which the 

 female did not pass through the last ecdysis. 



The succeeding acts of oviposition and delivery are described ; 

 they are repeated at regular and constant intervals, whereas the 

 later acts of" copulation are not so definitely arranged. A female 

 who has just deposited her ova, has a thin, faintly-coloured, hardly 

 detectable ovarian tube ; five days afterwards this is again filled, and 

 the red eye-spots of the embryos in the brood-cavity can be made out. 

 After ten days from oviposition, the embryos are ready for extrusion, 

 and again the ovarian tube will be found full ; for about two and a 

 half days the brood-pouch remains empty. 



The author does not look upon the development of the fat-body 

 as an arrangement which owes its origin to the struggle for existence, 

 but as a passive necessary result of the parasitic habits of these 

 animals; the assimilated nutriment which the free-living forms use 



