676 GREENE. [Vol. XV. 



The " occipital " row, oc, contains from nine to twelve sense 

 organs, sometimes with a pair of rudimentary phosphorescent 

 organs on the inner and outer side of each sense organ, some- 

 times with no phosphorescent organs. The row begins near 

 the posterior edge of the spinous dorsal, curves first inward 

 toward the median dorsal line, then outward and forward (see 

 PI. XXXVIII, Fig. I). 



In a species described from the Galapagos Islands, Porich- 

 thys nautopedium Jordan, the arrangement of phosphorescent 

 organs and sense organs corresponds, group for group, with 

 that given above. There are only slight variations from the 

 average number of organs, except in the pleural row, which, 

 like the pleural row of three specimens from Alaska (Table, 

 Nos. 8-10), is continued back to the base of the caudal. 



In the new species of Porichthys previously referred to, 

 obtained recently at Panama by Dr. Gilbert, the location of the 

 lines of phosphorescent organs and sense organs corresponds 

 very closely with that in Porichthys notatus. Also the num- 

 ber of both kinds of organs, as will be seen by a reference 

 to the appended table, Nos. 16 and 17, is very similar to the 

 number in the common form. It may be noted, however, 

 that on the dorsal surface, where in Porichthys notatus rudi- 

 mentary organs are found, phosphorescent organs are wholly 

 absent. The phosphorescent organs on the ventral surface 

 of this species are not more than half as large as in the 

 common species. 



In general, we may say that the phosphorescent organs of 

 the three species of Porichthys studied are always well devel- 

 oped and prominent along the ventral and ventro-lateral sur- 

 faces of the body, while along the dorsal surface they are 

 markedly small and rudimentary, and are very variable in 

 their development in the different specimens of the same 

 species. 



The sense organs, on the other hand, are quite constant both 

 in their presence and the extent of their development in the 

 different regions. The sense organs are accompanied by der- 

 mal papillae, two for each organ. These dermal papillae differ 

 very much in the extent of their development, being most 



