AGLAJA. 51 



disk (much fore-shortened in figure) oblong, wide, emarginate in 

 front, subtruncate behind ; free lateral margins 2-3 mill, wide, pos- 

 terior free margin wider. Posterior wings of mantle very large, 

 long, thin, the two membranous lobes broadly united by connecting 

 web, the left lobe bearing a short, flat flagellum. Gill (pi. 6, fig. 38, 

 seen from below) 11 mill, long (curved), with 11-12 branches on 

 each of the rhachis, alternately arranged, the branches on the con- 

 vex side nearly double as long as those on the concave side of 

 rhachis. Total length 40, breadth 20 mill. Length of head-shield 

 measured direct from front to back margin, 22 mill. 



Sandwich Is. (Nuttall). 



The great development of the posterior wings and the flat fila- 

 ment of the left one are characteristic. It differs from A. tricolorata 

 in having the tail-lobes broadly united, and the gill of different 

 structure if Vayssieres figure of the gill of that species be correct. 

 Description from one specimen ; shell not seen. Color in life un- 

 known. Fig. 37 is accidentally inverted. 



A. MACULATA d'Orbiguy. PL 6, figs. 40-43. 



Anterior and posterior disks of body black-brown ; posterior 

 mantle-wings greenish-brown with some small yellow spots ; foot 

 (fig. 43) greenish-brown with many unequal rounded spots of sul- 

 phur-yellow ; outside of parapodia the same color but spotless. 



Body thick, rounded ; back smooth, the anterior shield wide and 

 truncate in front ; posterior shield oval, smooth, terminating in 

 thick fleshy lobes, the right one wider. Foot fleshy, plicate, striate 

 and ridged transversely, smooth in front and distinctly emarginate. 

 Gill pyramidal, symmetrical, composed of a great many leaflets 

 bilobed at their ends. 



Length 3, width 2 centimeters. 



Valparaiso, Chili. 



Posterobranchcea maculata D'ORB., Voy. dans PAmer. Merid., p. 

 203, pi. 17, f. 6-9 (not f. 10). 



The view already expressed by Morch and Fischer in regard to 

 d'Orbigny's error in mistaking the back for the foot of this mollusk, 

 is undoubtedly correct. When this is righted, we find the charac- 

 ters of P. maculata perfectly normal for the genus Aglaia or Dori- 

 dium. 



