428 



PROCEEDINGS OF THE ACADEMY OF 



[July, 



Radula not examined. 



Integument with numerous minute photogenic organs, appearing 

 as dark bluish dots having a distinctly paler centre. These are 

 distributed as follows: (1) on the ventral surface of the mantle they 

 are everywhere exceedingly numerous and so evenly distributed 

 that a bilateral arrangement is only apparent after close examina- 

 tion, being even then not at all absolute; definite rows indistin- 

 guishable except for a narrow but distinct and fairly conspicuous 

 area entirely free of photophores and forming a straight longitudinal 

 band down the medio-ventral line with a fairly constant width of 

 scarce more than a millimeter throughout its course; the number 

 of photophores in one of the rows bordering it is from 42 to 45. 

 Laterally, the organs rapidly scatter and diminish in size until they 



Fig. 3. Abraliopsis scintiUans, dorsal aspect of gladius, natural size; [147]. 

 Fig. 4. Abraliopsis scintillans, portion of integument from ventral surface of 



mantle seen by reflected light, showing photophores and chromatophores; 



from an unstained mount in balsam; greatly enlarged; [147]. 



are only with difficulty to be made out at all. However, I have been 

 unable to find that they extend very much past the level of the eyes. 

 2. On the ventral aspect of the funnel the photogenic organs 

 are similar in character to those of the mantle, but are fewer in 

 number and therefore appear more symmetrically disposed. They 

 are ranked in about ten poorly defined longitudinal rows, variously 

 distant and containing 3-4 organs each, but the. arrangement of 

 the two lateral halves is alike and here again they are separated 

 by a clear space down the middle. 



