3IO DISCOVERY REPORTS 



luminous liver tubules ; and specimens of Hoplophonis novae-zealandiae and H. grim- 

 aldii with numerous well-differentiated superficial photophores. In some instances 

 either the whole or parts of the animal had been fixed in the Duboscq-Brasil modifi- 

 cation of Bouin ; otherwise formalin sea water had been used. It was found as the work 

 proceeded that the action of the formalin sea water had been somewhat erratic, fixation 

 occasionally being extremely good, but more usually indifferent or poor. Where possible 

 observations have been made on Duboscq-Brasil fixed material, the formalin-fixed 

 specimens being used for comparison. 



Later I received a single specimen of the rare Systellaspis affinis, preserved in formalin, 

 from the John Murray Expedition, and one specimen of Hoplophonis typus and three 

 of Systellaspis debilis, also in formalin, from the Dana Expedition. The specimens of 

 S. debilis were beautifully preserved with regard to external appearance, much of the 

 original pigmentation still remaining, particularly in the photophores. These, with the 

 specimen of 5. affinis, afforded the only instances in which pigmentation of the photo- 

 phores was observed after varying periods of preservation. 



The celloidin-parafiin method of sectioning has been almost exclusively used, and 

 sections were usually cut lo/i in thickness, although in some special cases sections as 

 thin as 5/< or as thick as lOO//, were found useful. Of the various staining methods 

 employed Mallory's triple stain, usually with the addition of a mordant for the acid 

 fuchsin (Anderson's modification), was found to be the most generally useful on 

 account of the valuable colour differentiation obtained between the various tissues. 

 For the details of nuclei, however, Heidenhain's haematoxylin was found necessary, 

 and other stains, such as Delafield's haematoxylin and picro-indigo-carmine, have also 

 been used. 



In studying the carapace organs of the species of Hoplophonis whole mounts, stained 

 in borax carmine or in paracarmine, were found to be of great value. 



Most of the drawings are based on a number of similar sections, and have been made 

 with the aid of a squared net micrometer eyepiece, or, in a few instances, by the use of 

 a projection apparatus. 



III. PENAEIDEA: SERGESTIDAE 



I. THE SUPERFICIAL PHOTOPHORES OF SERGESTES REGALIS GORDON 



In his notes on Crustacea made on board the 'Discovery' Dr Kemp recorded the 

 positions of a large number of " clearly circumscribed deep purple spots " on the surface 

 of the body of two large female specimens of a new species of Sergestes. The specimens 

 have since been described by Dr I. Gordon and the list of numbers and positions of the 

 purple spots quoted (Gordon, 1939). Dr Kemp says in his notes: "These purple spots 

 are probably luminous organs : portions of tissue containing them have been dissected 

 out and fixed in Duboscq together with a few of the appendages." Of these appendages 

 there came into my possession for examination one maxilla and the external ramus of a 

 uropod. The maxilla was described, with regard to the purple spots, as possessing three 



