216 Bibliographical Notice. 



jection of the " pulley "), the whole smooth ; end view elongate- 

 compressed ; extremities rounded. This much for a general descrip- 

 tion ; but it is further necessary to say that the lateral extremities of 

 the semicells somewhat taper ere becoming rounded off, and the 

 upper margins are notably retuse at middle. In the same gathering 

 occurred bodies in pairs, larger, more densely filled with green con- 

 tents, quadrate, with angles produced in a horizontal manner, and 

 surrounded by a rather dense common mucous investment. In 

 other words, these much resembled the Cosmarium just described ; 

 that is, they were formed, as it were, of very wide and but shallow 

 "semi-cells" connected by a very broad (notably broader than in the 

 Cosmarium described), nearly equally quadrilateral •* isthmus." Now 

 this looked very like another " form " of the Cosmarium, plumper, 

 stouter, broader, in fact more resembling the zygospore of, say, 

 Penium didymocarpum, only of a different colour (that is, of a bril- 

 liant) in place of a dull green, and by no means so thick-walled. 

 Indeed, though here likened to that zygospore, they could not be 

 at all mistaken the one for the other. A point of resemblance in 

 common was their occurring in pairs. However, Mr. Archer was not 

 disposed to regard these as truly another Cosmarium, or another 

 "form" of the same Cosmarium, but in reality the zygospore of 

 the first mentioned, occurring in twins or pairs, and in a general 

 wav a good deal resembling, as pointed out, that of Penium didy- 

 mocarpum. 



In only one instance, however, in the gathering were the empty 

 parent cells detected ; but here they seemed to be attached in a 

 similar manner at the outer angles as they are in the species referred 

 to. But, however curiously these may have resembled in outward 

 configuration the parent, they were not at all identical, the central 

 portion being much broader, the projections at the angles shorter 

 and narrower, the whole aspect more square or more equally quad- 

 rate, and the pairs of individuals combined in a hyaline but some- 

 what dense common mucous matrix. But as in only one instance 

 could the empty parent cells be detected, it is therefore not quite 

 certain that this is truly the zygospore of the former. At all 

 events, the first might stand as CosmaHum platyisthmum. 



Microphotographs of Bacteria. — Mr. K. J. Moss showed some 

 excellent microphotographs of Bacteria and of yeast-plant, from 

 a series he is making with a view to investigate the purity and 

 quality of brewers' yeast. 



BIBLIOGRAPHICAL NOTICE. 



Den NorsJce nor d-havs-expedl lion 1876-1878. VIII. Zoologi, Mol- 

 lusca. I. Buccinidce, ved Herman Friele. Med 6 plancher og 

 1 kart. 4to. Christiania : Grondahl and Sons, 1882. 



This is one of the last admirable volumes which have been pub- 



