NOTES ON THE PHOTOPHORES OF SERGESTES PREHENSILIS BATE. 3 I 5 



appears, making difficult the detection of the photophores with the naked 

 eye or under the lens. On the other hand, glycerin preserves the pigment 

 practically without change for an indefinite length of time, even when 

 heated over 40°C in that medium, so that Laubmann's 1 * method of intra- 

 vitam staining can not be brought into practice. In well dried specimens, 

 in which the general color is changed into a reddish orange, the pigment 

 is preserved to some extent. After the dissolving away of the pigment 

 granules forming the mantle, there is left behind a loose connective tissue 

 of the ordinary appearance. 



7) The thee ft. — Surrounding the pigment mantle on the proximal 

 side is the theca, which is simply a condensed layer of the general con- 

 nective tissue. In it the fibres run nearly parallel and concentrically, 

 showing a sprinkling of elongate nuclei. It passes, both inside and outside, 

 without delimitation into the same tissue of a much looser appearance. 

 Internally to the theca there is a noticeably more numerous occurrence of 

 the somewhat large granules which become blackened by Flemming's 

 fluid, than in the theca itself or in the general connective tissue. 



8) The tteree. — The exact mode of innervation of the photophores 

 I have not been able to determine. Certain it is that the nerve reaching 

 the organ does not perforate the pigment mantle as a single trunk. On the 

 other hand, it is very probable that the nerve, somewhat as in certain 

 (thoracic and abdominal) photophores of Euphausians, breaks up into 

 branches before it reaches the pigment mantle, and that these branches 

 severally pass into the mantle. Some slender fibres were observed 

 penetrating into the reflector from the internal convex side (fig. I, n) ; 

 they were probably of nervous nature. 



In conclusion, I should discharge the pleasant duty of expressing my 

 deep obligations to Professors Ijima, Watasé and Goto as well as to Dr. 



1) Laubmann, A. L., 1912. Untersuchungen über die Hautsinnesorgane bei decapoden 

 Krebsen aus der Gruppe der Carididen. Zool. Jahrb., Anat. Ont., Bd. 35, H. 1. 



