yol.2,pt. 2.] A. TAXONOMIC STUDY OF THE SALPIDAE METCALF. 87 



there is no trace of the optic plug or its pigment, and the rod-cells 

 in the ganglion are degenerate. 



The neural glands are more developed than in any other species 

 in the family (fig. 71), the disks and ducts both being larger, and the 

 epithelium within the disks being greatly thickened on the side 

 toward the ganglion. There are two pairs of well-developed out- 

 growths of cells from the ganglion, toward the disks, one pair (b) 

 containing small cells, the other (not figured) containing large cells. 

 The conditions are thus of the usual type, but the structures are 

 unusually well developed. 



SALPA MAXIMA, variety TUBERCULATA (new variety), aggregated form. 



Only aggregated zooids of this variety are recognizable in the 

 collections studied. They bear embryos indistinguishable from those 

 of the species type. The collections con- 

 tain about 50 specimens from station D. 

 5200, in the Mindanao Sea, Philippine 

 Islands, United States National Museum. 

 Cat. Nos. 6472 (Holotype) and 6454 

 (Paratypes) U. S. N. M. (aggregated form) 

 Ji&a£rossstation,D.5200Pamilacan Island, 

 vicinity western Bohol; April 9, 1908; sur- 

 face; surface temperature, 79° F.; surface 

 density, 1 .02468. 



The musculature of the variety agrees 

 with that of the species type; so also does 

 the structure of all the internal organs. 



Two characters distinguish the variety. 

 The anterior and posterior protuberances 

 from the body are as long as in any aggre- 

 gated zooids of Salpa fusiformis, though 

 they are of the distinctive S. maxima char- 

 acter, being more symmetrically placed and 

 more ventral than in S. fusiformis. The 

 second distinctive feature is the presence 

 of two areas of tough and thickened test 

 on the dorsal surface of the body on the fig.72.— salpa m ax™ a.vamety tuber. 



. i . i i n. -j »,i i » ,v , • 1 CULATA, AGGREGATED ZOOID, DORSAL 



right and left sides of the base of the atrial VIEW . ; c7l ECHINATE AREA 0F THE 

 siphon. These thickened elevated areas bear test, xn diameters. (Drawn by 

 numerous short triangular spines. The two 0YT * 0PKINS - 

 spinose areas are of different sizes, the one above the embryo being 

 about twice as large as the other. 



The possibility has been considered that this tuberculate variety 

 of Salpa maxima may be a hybrid between S. maxima proper and 



-em. 



: M$t-.---eck. 



-X--ini. 



