542 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 51. 



Specimens identified for me by Mr. Bryce as Metopidia parvula 

 represent a Spliagmim-form which falls within the variation limits of 

 L. patella. This is probably not true of the form described by 

 Montet ^ as M. parvula Bryce. The shallow ventral sinus, absence of 

 any dorsal sinus and the very large foot groove all indicate a very 

 distinct species. 



4. LEPADELLA LATUSINUS (Hilgendorf). 



Plate 91, figs. 7-12. 



Metopidia solidus latusinus Hilgendorf, Trans, and Proc. New Zealand Inst., 



vol. 31, 1899, p. 131, pi. 11, fig. 15d. 

 Metopidia latusinus Murray, Journ. Roy. Micr. Soc, 1911, p. 581, pi. 17, fig. 11. 

 Lepadella latusimis Harking, Bull. 81 U. S. Nat. Mus., 1913, p. 63. 



The body of this species is broadly oval or subovate in outline. 

 The dorsal plate of the lorica is strongly convex and evenly rounded, 

 with its edges shghtly overhanging the nearly flat ventral plate. The 

 width of the lorica is about three-fourths of the length of the dorsal 

 plate and is subject to only shght variations. The cross section of the 

 body is nearly semicircular, as the dorso-ventral depth is but Uttle 

 less than half the width. 



The distance apart of the lateral points of the head opening is about 

 one-fourth the length of the lorica. The dorsal smus is broadly 

 U-shaped and quite shallow, its depth not exceedmg one-third of the 

 width. The ventral sinus is deeply lunate, its depth being nearly 

 two-thirds of the width. There is a certain amount of variation in 

 the form of both the dorsal and the ventral sinus, as shown in figures 

 8-11. A stippled collar is present both dorsally and ventraUy. 



The length of the foot groove is one-third to one-fourth the length 

 of the lorica ; its form varies greatly. Anteriorly it is always evenly 

 rounded; the sides may be moderately divergent, as in figure 8, or 

 widely flaring, with the extremities recurved, as in figures 9 and 1 1 ; 

 the posterior width may be from one-third to two-thirds of the length 

 of the lorica. The lateral points always project beyond the lorica; 

 in the narrower forms they are nearly square, while in the extreme 

 varieties they show a strong outward curvature; in rare cases they 

 are even shghtly recurved. The posterior margin has in the nar- 

 rower forms a shallow median emargination ; in the widest forms a 

 very shghtly convex median lobe is interposed between two lateral 

 emarginations. In other words, from the lateral angles the posterior 

 margin always curves forward, the curvature being nearly constant 

 in all varieties, while the widest forms have a shghtly convex median 

 lobe, which gradually disappears as the total width decreases. 



The foot is stout and projects but little beyond the lorica; no 

 sensory pit has been observed on the terminal joint. The toes are 



1 Rev. Suisse Zool., vol. 23, 1915, p. 339, pi. 13, fig. 37. 



