I. '08. 68 



Avec uii semblable luxe d'organes phosphorescents, la 

 silhouette lumineiise de V Acanthephyra pellucida doit etre 

 dessinee d'urie maniere complete dans robscurite." 



The photophores mentioned in siections 2, 4, 5, and the latter 

 half of 7 bear the closest resemblance to those known in 

 A. debilis, but no trace is found of those described in sections 

 1 and the first half of section 7. The double row of luminous 

 points on the exopods of the pereiopods and pleopods (section 

 6) is represented in A . debilis by a single point at the base of 

 the exopods of the five legs and first pair of pleopods and, in 

 the last four pairs of the latter, by a similar point at. the base 

 of the endopod. On the third and fourth pairs of legs A. 

 debilis possesses a single photophore only — at the proximal 

 end of the carpus ; section 3 seems to imply that in A . pellu- 

 cida there are two, one on the basus and one on the propodus. 

 Many of the photophores present in A. debilis are not described 

 in the above account, the most important omissions being 

 those on the eyestalks, on the abdominal pleura and sternum 

 of the sixth somite, above the bases of the pleopods and on 

 the telson. There is no mention of the dark blue pigment 

 which seems to be invariably associated with photophores in 

 the Decapoda Natantia. A. pellucida is described as being 

 found " assez souvent a partir de -500 metres de profondeur." 



Perrier's account is very probably based on MS. notes by 

 Milne-Edwards, and it would not be surprising if it were 

 found to contain many errors. Two other species of Acan- 

 thephyra, A. (Systellaspis) lanceocaudata, Spence Bate, and 

 A. affinis, Faxon, are so extremely closely allied to A. debilis 

 that it is highly probable that they also possess luminous 

 organs. When the positions of the photophores on these two 

 species have been determined it may be possible to decide 

 on the validity of Acanthephyra pellucida. 



Genus Ephyrina, Smith. 



Ephyrina, Smith, 1885. 

 Tropiocaris, Spence Bate, 1888. 

 Ephyrina, Alcock, 1901. 



This genus may be readily separated from Acanthephyra by 

 the short, unarmed, elevated rostrum, and by the greatly ex- 

 panded ischial and meral joints of the pereiopods. 



Ephyrina Hoskyni, Wood-Mason. 



PI. VII, figs. 1-6. 



Ephyrina Hoskyni, Wood-Mason, 1891. 

 Ephyrina Hoskyni, Caullery, 1896. 



Ephyrina Hoskyni, Alcock, 1901, and hivesti gator, 1901, 

 PI. LII,' fig. 3. 



The rostrum is unarmed and has the form of a high thin 

 frontal crest ; it reaches but little beyond the middle point of 



