332 



DISCOVERY REPORTS 



exceedingly coiled and confused. Some of them make contact with the striated cone, 

 while others appear to extend peripherally around the photophore to its distal surface. 

 A distinct junction zone (Fig. io,j.s.) exists between the nerve fibres and the striated 

 zone. The precise mode of innervation is thus more complex than in S. debilis. 



The fibrils which extend around the photophore enclose it in a fibrous cup (Fig. lo, 

 f.r.) which is no doubt pigmented in life and acts as a reflector, or at any rate as a screen 

 preventing the inward passage of light. Numerous small, dense, and deeply staining 

 nuclei grouped around the photophore nerve bundle and basal part of the reflector may 

 be those of chromatophores and sheathing tissue. Superficially, on a level with the 

 photogenic cells, greatly elongate nuclei (Fig. lo, n.r.c.) lie among the fibres of the 

 reflector. On account of their position I have called them the nuclei of reflector cells, 

 but I am unable to off^er any suggestion concerning their function, unless they are 

 responsible for the secretion of one of the active principles of luminescence. I do not 

 think that they are necessarily concerned with the producton of the reflector fibres. 

 They are curiously distinct from the nuclei of the photogenic cells, being not only long 

 and narrow, but less rich in chromatin content and showing a linear sequence of 

 vacuole-like areas. Similar nuclei appear in a corresponding position in the pleopod 

 photophores of 5. affinis (p. 349) and S. debilis (my observations, p. 363 and the photo- 

 graph given by Kemp (19106, PI. Hi, fig. i)). 



It has already been mentioned that the annular depression of the integument around 

 the lens (p. 330) suggests the possibility of orientation of the photophore as a whole, 

 and that muscles capable of effecting this movement are present. Parallel with the photo- 

 phore nerve a longitudinal muscle (Fig. 10 and Plate XXV, fig. i, phot.l.m.a., Fig. 12, 

 phot.l.m.) extends to the integument of the limb just outside the annular depression. 



phot I m.s. 



Fig. II. Section through the longitudinal photophore muscle of the pleopod photophore of Hoplophorus 

 novae-zealandiae. phot.l.m.a. attachment of longitudinal photophore nrnscXt; phot.l.m.s. striated portion of 

 longitudinal mnsclt; phot. m. I. photophore muscle loop. 



