12 SMITHSONIAN MISCELLANEOUS COLLECTIONS 



withdrawal into a sheath. P eric era is nearly allied to Pisa; in fact, 

 P- bicorna is placed by some naturalists in one genus and by others 

 in the other. The peculiar character of the orbit, however, seems to 

 warrant the establishment of a new family division for the reception 

 of this genus and Tiarinia. 



7. TIARINIA CORNIGERA (Latreille) 



Platb III, Fig. i 



Pericera cornigera LaTrEillE, Encyc, x, 141. 



Milne Edwards, Hist. Nat. des Crust., i, 335. 

 Adams and White, Zoology of the Samarang, Crust., 

 18. 

 FTiarinia cornigera Dana, U. S. Exploring Expedition, Crust., i, no, pi. 

 Ill, f. 5. 



Our specimens differ from those described and figured by Dana 

 in having, at the summit of the intestinal region, one very large and 

 two inconspicuous tubercles, instead of three of equal size. They 

 are also much larger, some being nearly two inches in length. 



They are found on the reefs at low-water mark, and were collected 

 at the Amakirrima Islands by the officers of the steamer "John Han- 

 cock" and by myself at Loo Choo and Ousima. 



8. TIARINIA DEPRESSA Stimpson 



Plate III, Fig. 2 

 Tiarinia depressa Stimpson, Proc. Acad. Nat. Sci. Phila., ix, p. 217 [24], 

 i857. 

 Carapax in shape much like that of T. cornigera; proportion of 

 breadth to length, i : 1.5 ; form depressed; upper surface with tuber- 

 cles less numerous and more flattened than in the cornigera. There is 

 a small marginal spine on each side at the branchial region, above 

 which an arc of four depressed warts extends around the side; the 

 first (posterior) one largest, and placed a little behind the level of 

 the trituberculated cardiac protuberance ; the fourth, and smallest, 

 is near the anterior extremity of the branchial region, with a still 

 smaller one before it. A submarginal channel of some depth 

 passes around behind, above the intestinal region. Posteriorly, at 

 the upper or intestinal margin there is a subtriangular median 

 tubercle, with a smaller trilobate one on either side of it ; on the 

 lower margin there are four small tubercles. On the stomachal 

 region there are three warts in the median line, the anterior one 

 smallest, and placed some little distance before the others, with a 

 wart on either side of it; behind the posterior one there are two 



