ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 451 



The most important portion of the present report is an account 

 of the Idothaeid form Glyptonotus sahini. The mouth-organs, which 

 are well developed, are described in some detail ; the mid- is separated 

 from the hind-gut by a circular constriction which forms a valvular 

 projection into the enteric cavity ; the stomach is a bell-shaped tube, 

 only a little wider than the oesophagus, and it is shut off from the 

 intestine by a valve ; there are special muscles which compress the 

 stomach from side to side, and the presence within of spines and hairs 

 shows that we have to do with a masticating organ, but with one that 

 is very different from the complicated triturating apparatus of the 

 Oniscidas ; this is to be correlated with the difference of nutriment. 

 In addition to the tubes of the hepatopancreas there are glands of 

 another kind which have not hitherto been detected in the Isopoda ; 

 those around the mouth have, under the Microscope, the appearance 

 of spherical or elongated glands, not unlike those seen by Glaus in the 

 Phronimidge, and by P. Mayer in the Caprellidge. The author is 

 unable to give any definite opinion as to their function, as he is in 

 doubt whether they secrete mucus which aids in the movement of the 

 mandibles, or produce an enzym which acts on the albuminous and 

 starchy bodies that have been cut small by the mandibles. 



The ovaries are of the form common among the AmphijDoda and 

 Isopoda, and are long tubes, lying laterally above the enteric canal. 

 The genital orifice does not appear to be permanently but only 

 temporarily open ; a similar arrangement to this has been detected by 

 Schobl in the Oniscidse. Weber enters with some detail into the 

 account of the female organs and the brood lamellae. The copula- 

 tory organs of the male are very similar to those of the terrestrial 

 isopods, the penis being long and stylet-shaped ; in some males the 

 penis was seen to be rudimentary, and this appearance is considered 

 to be correlated with an ecrlysis ; small examples, recognized to be 

 males by the presence of spermatozoa in their testes, had the external 

 appearance of females. The sexual characters are fully described. 



The investigation of the nervous system was attended with con- 

 siderable difficulties, owing to the richly calcareous condition of the 

 carapace preventing the complete preservation of the specimens in 

 spirit. As is well known, the brain of isopods differs a good deal from 

 that of other Crustacea — so far, at least, as we have been able to 

 judge from what is known of the Oniscidje. In Glyptonotus the 

 "optic ganglia" were at first thought to be absent, but treatment of two 

 specimens with osmic acid revealed the fact that they had undergone 

 alteration only ; at the point where they are found in the Oniscidse 

 there was seen a pyriform body, which gave off an extremely fine 

 filament which ended at the point where the eye would have been 

 expected to be, had it been present ; this cord is clearly a rudimentary 

 optic nerve. The rest of the brain is not changed in form by the loss 

 of the eyes and the reduction of the optic ganglia. As a compensa- 

 tion for the loss of the eyes the olfactory apparatus is well developed 

 in the male. 



Glyptonotus sabini is obviously a common arctic species. 

 The male of Murmopsis typica has, M. Sars has pointed out, the 



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