70 SUMMARY OP CURRENT RESEARCHES RELATING TO 



of Isopods and Ampliipods is a syneerebrum, the components being the 

 brain proper or procerebral lobes, the optic ganglia, and the first and 

 second antennal lobes ; as compared with the Decapoda, these lobes 

 are quite separate from each other. The author prefers to use the 

 term procerebrum, as the lobes are not the homologues of the cerebral 

 lobes of vertebrates ; they are more than twice the size of any of the 

 other ganglia ; the eyes of Asellus being small, the optic lobes and 

 nerves are small also. The mouth-parts in the Asellidae, if not all 

 the Isopoda, are not innervated from a single subcesophageal ganglion, 

 but each appendage is supplied by a nerve arising from a separate 

 ganglion. 



In Cecidotsea the optic ganglia and nerves are lost, while the eyes 

 have lost their retinal cells ; very rudimentary lens-cells are still 

 inclosed in the black pigment-mass. 



" The steps taken in the degeneration or degradation of the eye, 

 the result of the life in darkness, seem to be these : — (1) The total 

 and nearly or quite simultaneous loss by disuse of the optic ganglia 

 and nerves. (2) The breaking-down of the retinal cells. (3) The 

 last step being, as seen in the totally eyeless form, the loss of the 

 lens and pigment." Dr. Packard thinks that a modified modern 

 form of Lamarckianism will account for the origination of these forms. 



Processes formed by Cerapus on Tubularia indivisa.* — Prof. 

 W. C. Mcintosh finds that the domicolous Amphipod Cerapus sp. 

 constructs groups of flexible tubes on stems of Tubularia indivisa; 

 unlike those made by G. ruhricornis they are partly composed of 

 grains of sand, spines and bristles of annelids, hairs of sea-mice, and 

 fine horny fibres. On the same stems are processes which project 

 from the coencecium like branches, three to four inches long, smoothly 

 rounded ; they are usually at some distance from the nests or tubes 

 of the crustaceans which climb actively on them ; it is unknown 

 whether their function is to aflbrd a larger area for the capture of 

 prey or a more extensive surface for the resting of the minute forms 

 which serve as the crustacean's food ; but it is probable that they sub- 

 serve some useful purpose. Unlike the equally peculiar spinous 

 processes which are not uncommon on the tubes of annelids, they are 

 not to be credited with a protective function. 



Vermes. 



Development of the Trochophore of Eupomatus uncinatus.f — 

 Dr. B. Hatschek has investigated the history of the larva of this 

 Serpulid, the study of which has suggested to him that the auditory 

 vesicles had appeared in the " Trochozoon " and had been thence 

 inherited both by molluscs and annelids. The larva in question has 

 a peculiar ectodermal vesicle at its hinder end. 



It is found that most of Stossich's observations on this worm are 

 incorrect, and that author appears to have had to do with abnormally 

 developed embryos. 



* Ann. and Mag. Nat. Hist., xvi. (1885) pp. 484-5. 



t Arbeit. Zool.-Zoot. lust. Wien, vi. (1885) pp. 121-48 (5 pis.). 



