ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 55 



some other groups of invertebrates, may have originally diverged 

 from an ancestral vermiform stem, such as the remarkable worm-like 

 mollusc, Neomenia would denote." He lays stress on the brachio- 

 podous individual being the product of a single ovum, and not giving 

 rise to others by gemmation. He considers that the shell, the pallial 

 lobes, the intestine, the nerves, and the atrial system afford characters 

 amply sufficient to define the class. The greatest depth at which a 

 living species has been found alive has been 2990 fathoms. 



As to classification, he groups the recent species in two great 

 divisions, viz. : — I. Anthropomata (Owen) = Clistenterata (King) ; 

 II. Lypomata (Owen) = Tretenterata (King). The Anthropomata 

 he divides into three families : — (1) Terebratulaceae, with seven sub- 

 families, thirteen genera and subgenera, seventy species, and twenty- 

 one imcertain species; (2) Thecideidfe, with one genus and two 

 species ; (3) Ehynchonellidte, one genus, one subgenus, and eight 

 species. The Lypomata he also divides into three families, five 

 genera and subgenera, twenty-three species, and seven uncertain 

 species : — (1) Craniidse, with one genus and four species ; (2) Dis- 

 cinidse, with one genus, one subgenus, and eight species; (3) Lingulidse, 

 with one genus, one subgenus, and eleven species. He does not 

 accept M. Delongchamp's scheme (1884) of classifying the Terebra- 

 tulina, bringing forward Mr. Call's observations on Waldheimia 

 floridana of delicate spiculae in the floor of the great sinuses as telling 

 evidence against the arrangement. The various genera and species 

 are then dealt with, followed by remarks on the Terebratulaceae, with 

 copious descriptions and observations. 



Arthropoda. 

 o. Insecta. 



Development of Reproductive Organs in Insects.* — The pre- 

 cocious appearance of the reproductive organs of insects has been 

 repeatedly noted since Suckow first remarked it in the Lepidopteran 

 embryo. The fact acquired greater interest when, in 1865, Leuckart 

 and Metschnikofif observed in the viviparous larvsa of Cecidomyige that 

 the polar globules formed the pseudovarium, a discovery afterwards 

 confirmed (1870) by von Grimm in the case of a parthenogenetic 

 Chironomus. Prof. E. G. Balbiani further corroborates this origin of 

 the reproductive organs in a sexually- produced and producing species 

 of Chironomus. 



He describes at length the laying of the band of eggs and the 

 elastic attachment by which they are kept below water, the appear- 

 ance of the newly laid ova with cleai peripheral layer and granular 

 central mass, the gradual retraction of the vitellus from the enclosing 

 membrane, the consequent formation of a space filled by the liquor 

 viteJli, the successive or rarely simultaneous expulsion of the polar 

 globules, the characteristics of these globules with their refracting 

 granules and clear nucleus, their immediate division into eight, and 



* Reciieil Zool. Suisse, ii. (1885) pp. .^27-88 (2 pis.). 



