MORPHOLOGY. 
Crust. 19 
direct to the pericardium. As in Mysis forms, the membrane of the 
carapace is used as a respiratory organ. This organ permits land-crabs 
to live long out of the water. 
Andrews has experimented upon crabs, with a view to investigating 
their power of throwing off limbs. The action has its reflex nervous 
centre in the thoracic mass. Autotomy always occurs at a fixed spot — in 
the second joint of the appendage. This spot may correspond to the 
second joint of Macrura , as the second and third segments of the 
macruran appendage are fused in Bracliyura. There is a definite plane 
of rupture, with a modification of the exoskeleton and an internal mem- 
branous septum. 
Excretory Organs. 
Marchal (1) has some new observations on the green glands of the 
Crayfish. The septa of the saccule are so arranged that its cavity has a 
racemose form, the two main lobes being separated by a large median 
septum. The green substance is a plexus of anastomosing canals giving 
off diverticula which end in ampullae. With regard to the white sub- 
stance, Wassiliew’s views are maintained, as against those of Szigethy 
and Rawitz. 
Marchal describes the excretory organs of various decapod forms : 
Carcinus (1), Homarus , Palcemon , Pagurus, Galathea, Stenorhyncus (2), 
Palinurus , Gebia , and Crangon (3). 
Marchal (4) considers: — (1) That the operculum of the excretory 
orifice of Bracliyura is homologous with the first joint of the antennae of 
Macrura. (2) The basilar peduncle of the antenna consists funda- 
mentally of five joints in both groups. (3) The exopodite exists in a 
rudimentary form in many types ( e.g Galathea ), where it is generally 
considered to be absent. 
Alimentary System. 
Costes discusses the glands connected with the alimentary canal of 
Decapoda. He finds in some forms, but not in Macrura , a gland hitherto 
undescribed, at the anterior part of the sternal plastron. It is analogous 
to the intestinal glands, but its cells are filled with numerous spherical 
globules. The external opening of the gland is either on the sternal 
plate, or just in front of the first maxillipede. 
Generation and Development. 
Herrmann has studied the spermatoblasts of Decapoda. He obtained 
satisfactory results by placing the contents of the testicles in a drop of 
blood-serum from the animal, and exposing them to the vapour of strong 
osmic acid. The male ovule is described, and its division by karyokinesis 
into spermatoblasts, which, again, develope into spermatozoids. The 
forms peculiar to various decapod types are described. 
