454 



SCIENCE 



[N. S. Vol. XXVII. No. 690 



composed of two cells, and that their his- 

 tological conditions are so nearly identical 

 with those of the median eye, composed of 

 three ocelli, that they must be regarded as 

 organs of vision rather than of audition. 

 The retinal cells of the median eye and of 

 these organs both present peculiar basal 

 plates, and the cytoplasm of the cells shows 

 a marked but fine striation, which Hesse 

 has erroneously regarded as homologous 

 ■with the " Stif tchensaum " which he dis- 

 covered in the eyes of many invertebrates. 

 Esterly regards this striation as the expres- 

 sion of a structural condition due to the 

 secretive activity of the retinal cells in pro- 

 ducing the basal plates. The "Binnen- 

 korperchen" of Hesse, or phaosomes, are 

 present in the organ of Glaus as well as in 

 the ocelli, and are thought to be of im- 

 portance in light reception. 



There are ten retinal cells in the ventral 

 ocellus, and nine in each of the lateral 

 ocelli composing the median eye. From 

 the basal-plate end of each cell emerges a 

 single nerve fiber, these twenty-eight nerve 

 fibers constituting the single optic nei've of 

 the median eye. Two nerves emerge from 

 each organ of Glaus, one from that surface 

 of each retinal cell which is opposite its 

 basal plate. In this particular the organ 

 of Glaus differs from the ocelli, the former 

 being eyes of the inverted tj^e, whereas the 

 ocelli are— contrary to the opinion of 

 Hesse— not inverted. The neurofibrillse 

 appear to end in the retinal cells in beaded 

 fibers having terminal club-shaped enlarge- 

 ments, -yphich often have an intimate rela- 

 tion to the phaosomes. This suggests a 

 possible functional relation between the 

 two. 



Six plates of original drawings by the 

 author and reproductions of them by the 

 photogravure process (A. W. Elson & Go.), 

 together with some of the preparations, 

 were exhibited. 



The Luminous Organ of a New Species of 



Anonwlops: Ulric Dahlgken, Princeton 



University. 



The fish was taken by the writer in 

 moderately deep water off the north coast 

 of Jamaica, B. W. I., in March of last 

 year. It will be described and named by 

 Mr. G. F. Silvester, of the Princeton 

 museum. 



The fish shows several whitish spots on 

 parts of the body and these spots may have 

 a luminous function. This could not be 

 determined. 



The main luminous organ consists of two 

 large "photophores" placed one under 

 each eye. The photophore lies close to the 

 eyeball and may be said to be a part of the 

 under lid. When first seen it gives the 

 impression of being a foreign substance in 

 the eye and the native fisherman would not 

 believe that it was not a worm. The 

 length of the organ was about the diameter 

 of the eye and it was oval in form. Its 

 color was cream white and the presence of 

 a large blood supply directly on the sur- 

 face was noticeable in the form of a retic- 

 ulum of red lines on what was apparently 

 the outer surface. 



The entire organ was somewhat loosely 

 fixed and could be rotated laterally down 

 under an edge of integument so as to be 

 almost entirely concealed. The part under 

 which it slipped had a thickened edge and 

 could be regarded as a means of suddenly 

 shutting off the light when it was necessary 

 not to show it. 



The structure of the organ can be very 

 well made out in a single section taken 

 transversely to the long axis of the animal's 

 body and therefore to the longer axis of 

 the photophore. This shows that the 

 largest mass of the organ consists of a close 

 set and parallel set of simple tubular 

 glands reaching from the outer to the inner 

 surface of the structure. These glands are 



