ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
331 
also absorbed ; that the muscle-cells undergo partial degeneration — es- 
pecially nuclear — before they fall victims to the phagocytes ; that the 
free phagocytic cells behave in two ways ; some devour the dead muscle- 
cells (and probably also the notochord-cells), while others serve for 
absorption of yolk and form packets along with the endoderm-cells. 
Salensky calls these “ necrophagocytes ” and “ synphagocytes ” respec- 
tively. 
The author’s general conclusion is that the buds of Distaplia are 
homologous with the buds of other Ascidians and with the stolo prolifer 
of the metagenetic Tunicates, representing a transition between these 
two forms of asexual reproduction. He believes that the nurse-genera- 
tion of metagenetic Tunicates has arisen from the larval stage of ascidian- 
like forms, which had the power of multiplying by buds, and attained 
sexual maturity, and that the stolo prolifer of metagenetic Tunicates 
has arisen from a bud in which budding has been replaced by fission. 
Visual Organ of Salpa.* — Sig. F. Todaro is convinced as to the 
structural correspondence between the visual organ of Salpa and the 
Vertebrate eye. The organ in question consists of a pigmented layer 
and a retina, derived from a common rudiment which arises by delami- 
nation from the upper part of the cerebral vesicle. In the aggregate 
forms it is transformed into a variable number of secondary eyes, some 
of which are rudimentary. These also vary from species to species. 
The primitive eyes or the well-developed secondary eyes show the 
following layers : (1) a layer of nerve-fibres (the cerebral part) ; (2) a 
nuclear layer of visual elements ; (3) a layer of supporting rods, cuticular 
modifications of the epithelial cells and (4) a pigmented layer. The 
supporting rods are comparable to those in the Vertebrate eye. An 
answer to the recent observations of Goppert and Metcalf, who deny any 
homology between the visual organ of Salpa and the Vertebrate eye, is 
promised in a forthcoming memoir. 
Arthropoda. 
Classification of Arthropoda.f — Mr. J. S. Kingsley proposes a 
scheme of classification which he thinks adequate to the present state of 
our knowledge of this group. The first sub-phylum of Branchiata con- 
tains the two classes Crustacea and Acerata; the former are divided 
into two sub-classes, the Trilobitse or Palaeocarida, and the Eucrustacea — 
a term for which we cannot say sit venia verbo. For the latter, Grobben’s 
classification is adopted as follows : — 
Super-order I. Phyllopoda. 
Order 1. Euphyllopoda. 
„ 2. Cladocera. 
Super-order II. Estheriaeformes. 
Order 1. Ostracoda. 
Super-order III. Apodiformes. 
Order 1. Copepoda. 
„ 2. Cirripedia. 
Super-order IV. Malacostraca or Branchipodiformes. 
* Atti R. Accad. Lincei (Rend.), 1893, pp. 374-81 (1 fig.), 
f Amer. Natural., xxviii. (1894) pp. llS-35, 220-35. 
