THE INTERNAL ANATOMY OF BATHYNOMÜS GIGANTEÜS. 

 WITH A DESCRIPTION OF THE SEXUALLY MATÜUE 



FORMS. 



By R. E. Lloyd, M.B., B.Sc, Captain, I. M.S., formerly Surgeon Naturalist, 



Marine Survey of India. 



INTRODUCTION. 



In the year 1878 the naturaHsts of the U. S. Survey Ship ''Blake" obtained 

 the first example of Bathynomus giganteus. This specimen, an immature male mea- 

 suring 23 cms. in length and 10 cms. in breadth, was taken from 955 fathoms in the 

 Carribean Sea. In the following year Milne Edwards (i) published a short account 

 of it and defined the genus. It was not until 1902, however, that a full description 

 of the external characters was published by Milne Edwards and Bouvier, in an 

 admirable monograph (2). In the preparation of this work, the authors had at 

 their disposal the original ''Blake" specimen, and two examples of a new species, 

 B. döderleini, from an unrecorded depth in Sagami Bay on the coast of Japan. The 

 authors also refer to the capture of three immature female specimens, in the Lacca- 

 dive Sea off the West Coast of India (3). The monograph contains a full historical 

 summary on the subject of Bathynomus, in light of which further introductory 

 remarks are superfiuous. 



The present memoir treats of Bathynomus chiefly in regard to features other 

 than those described by M. Bouvier. The subject will be treated under the following 

 headings : — 



1. A description of the internal anatomy of the genus. 



2. A description of the external characters of the sexually mature egg-bearing 



female and of the mature male. 



3. On certain differences between the Indian and American forms of Bathy- 



nomus. 



4. The occurrence and distribution of the species in Indian seas. 



5. A few notes on the natural history of the genus. 



I.— THE INTERNAL ANATOMY. 



Preliminary. 



During the last two years, the R.I.M. Survey Ship " Investigator" has obtained 

 four more specimens of Bathynomus giganteus from three widely separate stations; 



