588 RKroiiT — 1898. 



has been published during the past year, but several are in course of 

 preparation. 



2. Of the ' Mittheilungen aus der zoologischen Station zu Neapel,' 

 vol. xii., part 4, with 12 plates; and vol. xiii., part 1, with 11 plates, 

 have been published. 



.3. Of the ' Zoologischer Jahresbericht,' the Bericht for 1896 has been 

 published. 



4. A new Italian edition of the ' Guide to the Aquarium ' has been 

 published. 



The details extracted from the general report of the Zoological Station, 

 which have been courteously furnished by the ofl&cers, will be found at the 

 end of this report. They embrace lists (1) of the naturalists who have 

 occupied tables since the last report, and (2) of the works published during 

 1897 by naturalists who have worked at the Zoological Station. 



I. — The Pseudohranch and Intestinal Canal of Teleosteans. 

 By James F. Gemmill. 



I occupied a table at the Naples Zoological Station between the end 

 of August and the beginning of November, 1897. My work there had to 

 do mainly with certain points in the anatomy of the osseous fishes ; in 

 particular, with the distribution, structure, and development of the pseudo- 

 branch, and with the intestinal canal. Over fifty species of teleosteans 

 were examined. 



A. Pseudohranch. , 



As far as the general anatomy and relations of this organ are con- 

 cerned, I could only, in the case of the greater number of species examined, 

 go over ground which was worked out long ago by Joh. Miiller. Records 

 were, however, made for a certain number of species not included in his 

 list. But in every case, which was carefully examined, the great fact 

 established by Joh. Miiller that the pseudohranch is supplied by 

 oxygenated blood was found to hold good. Comparative details as to the 

 presence and degree of modification of the pseudohranch were specially 

 noted whenever possible in allied species and genera. In this connection 

 the flat fishes were found to form an interesting group. On the whole a 

 good series of stages was obtained, illustrating on the one hand the gradual 

 disappearance of the organ in question, and on the other its passage 

 from a free projecting condition to one in which it is encapsuled and 

 glandular. 



The microscopical structure of the organ was investigated in a certain 

 number of species. The results obtained agree in the main with what 

 had Ijeen previously described, but there was also found in some cases 

 {e.g. Serranus gigas), external to the layer of large polygonal cells 

 which lies superficial to the capillaries in each lamella, another layer of 

 flattened scale-like cells. These persist even when the pseudohranch 

 becomes encapsuled and glandular, though in that case they do not form 

 a continuous stratum, but are represented by scattered squamous cells 

 lying between adjacent lamellaj. 



A study of the development of the gland in Hippocampus hrevirosiris 

 and Syngnathus acus by the method of serial sections of embryos was 

 begun. The lophobranch group was chosen for investigation, because in 

 the adults of this group the pseudohranch presents every appearance of 



