ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 339 



were not detected by the autlior. There is a pair of hepatic tubes 

 which give rise to numerous enlargements and lobes, but no lateral 

 enlargements are to be found in the males. 



There is a well-developed heart in the form of a rounded oviform 

 sac; in the irregularly developed female there is to be detected not 

 only an asymmetry of form, but also of the position of the clefts. 

 The wall of the aorta is formed by a clear transparent membrane, 

 which never exhibits contractions ; though efferent vessels are present, 

 there are no afferent ones; a septum of connective tissue extends 

 transversely below the enteron, just as in the Phronimida. 



The nervous system has only been examined by Eathke, and by 

 Cornalia and Panceri ; in its morphological relations it differs com- 

 pletely from that of the other Isopoda ; the brain is extremely 

 reduced, as are all the parts connected therewith ; in the third thoracic 

 segment is a reduced unpaired ganglionic chain, formed by the short- 

 ening of the longitudinal commissures and the fusion of the ganglia ; 

 in this seven distinct elements may be made out. The peripheral 

 nerve-trunks have a somewhat peculiar ganglionic relation. Those 

 of the first go directly from their proper ganglion to the most anterior 

 thoracic segment ; the second pair passes below the third ganglion, 

 and the next near the sixth, or, in other words, just in front of the 

 termination of the nervous plate. The sensory organs are either a 

 great deal reduced or have completely disappeared; in the young 

 free-swimming male there are eye-spots and jointed, paii'ed, antennae ; 

 there is some question as to whether eyes can be said to exist in the 

 female ; at any rate true optic nerve-fibres are not always to be made 

 out. The larvfe have reddish pigment-specks at the sides of the 

 cephalic lobes, which are covered over by the base of the outermost 

 pair of antennae. 



Not only do these parasites retain a separation of the sexes, but 

 there is a well-marked sexual dimorphism ; the ovaries are dorsally- 

 placed tubes, not fused with one another, the appearance of which 

 varies with the age and condition of the animal ; at first they are 

 straight, but they gradually become provided with a number of lateral 

 saccular diverticula, which project into the thoracic segments ; the 

 orifices of these organs are found, as might be expected, on the inner 

 side of the bases of the iifth pair of legs. The wall of the ovarian 

 tube is a thin membrane, invested internally by an epithelium and 

 completely transparent. The male organs have much the same 

 general characters as the female ; and the tube functions both as 

 germinal gland and receptacle for the sperm ; the spermatozoa are 

 very small granules, immense numbers of which are collected into 

 one mass. No formation of spermatophores, or any copulatory organs 

 have been detected. 



After referring to the musculature and the connective tissue, the 

 author passes to the second part of his essay, where he deals with 

 the classification of the Bopyridte : owing to the small number of 

 species it is not necessary to form any subfamilies ; the difficulties 

 of definition lie in the fact that the form of the body, the number of 

 antennary joints, and the arrangement of the gills differ so much iu 

 the two sexes. 



