ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 777 



form — forced in a mass with, the nutritive liquid through the plexuses 

 of the body — hut they glide almost in the form of parasitic amcebaj 

 over the muscles and the organs, nourished by the liquid of the body. 

 In this form the author has observed them in Cyclops without a 

 heart, as well as in the Calanidao (Diaptomus) which have one ; it is 

 therefore very probable, or even certain, that they exist in the whole 

 of the Copepoda. They are mesoblastic cells in movement during 

 the whole of life, which participate, from their earliest stages, in the 

 formation of the muscles and genital canals. 



It is proposed to divide the genus Cyclops into two natural groups. 

 The principal differences exist in the larval states of the nauplius and 

 metanauplius, in which the characters are so different and so marked 

 at first sight, that the possibility of a mistake is entirely excluded. 

 The principal difference consists in the organization of the limbs. 



In one of these groups — the Dolichopoda — which is evidently the 

 oldest, all the limbs serve for locomotion, and only a few spines on 

 the second and third pairs are for seizing nourishment. The second 

 group — the Brachypoda — on the contrary is more perfectly organized ; 

 it is especially the third pair which is bent in the form of maxillaa 

 and adapted exclusively for seizing nourishment. The spines also, 

 at the base of the antennae of the second pair, are adapted for this 

 function. Whereas in the first group all the limbs extend far beyond 

 the margin of the body, and the third is furnished with a long 

 natatory branch, in the other group they are very short and robust, 

 with the natatory appendage on the mandible very rudimentary. 



Aberrant Oniscoids.*- — The wood-lice are much neglected by 

 English naturalists. They are well worthy the attention of micro- 

 scopists who are not able to visit the seaside, and yet desire some path 

 of inquiry affording more promise than the beaten anatomical tracks. 



As a sample of what may be done in this direction we note a 

 memoir by Dr. Max Weber on Haploplithalmus and Trichoniscus, 

 genera enrolled in the exceptional sub-family of Trichoniscidse. The 

 structure of Trichoniscus, save in regard to externals, had not before 

 been investigated. The copious details which such an essay contains 

 must necessarily be studied in the original. Points of general interest, 

 affecting other isopods, are duly indicated. 



Dr. Weber makes a digression, more than eight pages long, on the 

 subject of chromatophores. Leydig first showed that in the same 

 situations as chromatophores are found cells without pigment, but 

 otherwise similar, the whole forming one common system. Also 

 animals of constant tint possess non-contractile cells, presumably 

 homologous with chromatophores. Nerves are unquestionably distri- 

 buted to the chromatophores. By means of gold chloride Dr. Weber 

 has proved this connection in the case of a common isopod (a young 

 Philoscia). Anger, fear, love and other emotions undoubtedly cause 

 animals with chromatophores to change colour ; yet it is usually 

 assumed that the play of the chromatophores serves to hide their 

 possessor, and perhaps in some cases for protection. But Leydig saw 



* Arch. f. Mikr. Anat., xix. (1SS1) pp. 579-G48 (2 pis.) 



