2 Crust. 
X. CRUSTACEA. 
INTRODUCTION. 
Where so many of the papers published in any year are devoted to the 
description of new and the rcdescription of known species, it is always 
difficult to estimate aright the progress made in our knowledge of a group. 
This is especially true of the Arthropodan sub-divisions — Crustacea , 
A rachnida, and Myriopoda. The Record of the first-named for 1897 is 
slightly larger than that of 189G, consisting of 208 papers. Of these 104 
deal with species, and a number of others consist of faunistic lists. 
Papers dealing with Plankton Crustacea are fairly numerous. The 
reader is referred to those by Zacharias (204-206), and by Pitard on 
the freshwater Plankton of certain Swiss Lakes (128-131). Kofoid (92), 
in Science, criticises the present methods of Plankton collecting, pointing 
out very serious defects. 
Garstang (63, 64) continues the publication of results obtained last 
year on the respiratory adaptations of certain Decapoda. Ilis papers 
have an important bearing on the question of the utility of specific 
characters, and are therefore of general interest. Bohn (13, 14) also 
deals with certain points in the respiration of Crustacea. 
An interesting discussion has been carried on in the pages of Natural 
Science, entitled “Are the Arthropoda a natural group?” Many eminent 
specialists on the various classes have contributed to the discussion. The 
conservative view is strongly advocated by Ray Lankester (95). 
Jaworowski (87) deals with his theory of Arthropodan appendages, and 
Bouvier (19), in an important comparative study of the . Dromiacece , gives 
reasons for the view that Crabs are derived from Lobster-like ancestors. 
There are no other papers dealing with morphological theory. 
Embryology is considered by several authors: Brandes (24, 25) de- 
scribes the spermatozoa and reproduction of Decapoda \ Butciiinsky (27) 
gives an important account of the segmentation of the ovum in Nebalia ; 
and Samassa (153) of the winter eggs of Cladocera. Stingelin (187), in 
a paper dealing with variation, publishes some observations on the repro- 
duction of Cladocera. 
The histology of the muscle-fibre of Cirripedia has been studied by 
Gruvel (72). Miss Newbigin (112) describes the pigments of Decapoda 
in the Journal of Physiology. 
The present Record contains seven papers dealing with the Crustacean 
nervous system and sense-organs. These comprise Carlton’s (29) mono- 
graph on the “Brain and optic ganglion of Leptodora ,” Bethe’s (8) 
description of the nervous system of Carcinus mcenas , Nussbaum & 
Schreiber’s (118) work on the “ Peripheral,” and Zograf’s (208) on the 
“Embryonic nervous system of Crustacea ,” and lastly, Steuer’s two 
papers (177, 178) on the “Anatomy and physiology of the eye of 
Corycceus .” 
The placental parasitism of the Monostr ill idee has been studied, both 
in its special and general aspects, by Giard (65, 66), who also gives an 
account of the ontogeny of this group (69). 
Janet’s interesting papers on the animals commensal with Ants (84, 
85) must not be omitted. He describes several species of terrestrial 
Isopods found in their nests, and his papers are remarkable for the 
amount of patient observation they reveal. 
Subterranean and cavernicolous Crustacea are considered at length by 
Dollfus (45), and by ViRis (190, 192, 193), who also discusses the degeneracy 
of their sense-organs and general adaptation to their environment. 
Giard (67) deals with the phenomena and probable parasitic cause of 
autotomy or self-mutilation amongst Crustacea. 
Foremost amongst systematic works must stand Hansen’s “ Monograph 
