1916.] NATURAL SCIENCES OF PHILADELPHIA. 57 



Remarks. — In spite of its wholly dissimilar gladius, this Little 



species reminds one more strongly of the two Lycoteuthid genera, 



Lycoteuthis and Nematolampas, than any other group, and this is 



probably due to the one fact, more than any other, thai the photo- 



genic complexes are so strikingly similar. That of the L. megaleia 



is accordingly summed up in the accompanying table, which also 



repeats the figures for L. diadema and N. regalis given in my earlier 



paper. 



L. 

 Position of Photophores. diadema. 



< »m ryes: 



Ventral periphery 10 



Lateral 



( )n arms: 



Tips of dorsal arms 



Tips of dorso-lateral arms 



Ventrolateral arms 



( hi tentacles: 



At base 



Along the stalk i 



Within pallia! chamber: 



Anal 2 



Branchial 2 



Abdominal 1 4 



Posterior extremity of body 



Total 22 90+ 23 



Although in each of the three species subocular, tentacular, and 

 intrapallial organs are well developed, the table helps to emphasize 

 differences which may be more important than the similarities. 

 Then again, although I have not yet had opportunity to work out 

 the histology of any of these structures in Lampadioteuthis, the 

 external appearance of its tentacular photophores is not at all like 

 the deep-seated organs of the Lycoteuthids, while the curious organs 

 protruding from the base of the tentacles fail to resemble anything 

 known to me. The single pair of enormous silvery photophores at 

 the base of the gills is also distinctive as contrasted with the belt of 

 five smaller organs possessed by the Lycoteuthid genera. 



The occasion is very tempting to add a little generalizing on the 

 possible significance of such striking differences in the luminous 

 pattern of cephalopods, especially since the constituent organs are 

 so evidently polyphyletic in origin, but this had best be reserved 

 for some future opportunity. 



1 I have followed prevailing usage in classifying the series of three organs 

 situated between the branchial pair in Lycoteuthis and Nematolampas as abdomi- 

 nal, though it seems to me more rational to consider them in relation with the 

 branchial organs than with the isolated posterior organ. 



