K \ in M:IN \ il 



longitudinally striated at t lie apirrs ,-raly at the sides ; lateral areas 

 hi-lirate. tin- line scaly. Posterior valve very small, nearly 

 eealed. iobquadtate, hi-liratr. (iirdle wide, gray, pilose, elothed 

 with whitish down ; tutts !l, white, ^h 



Length 27, breadth 1(5 mill. (Rochebr.) 



\'--w Caledonia (Presented to the Paris MILS. by tin- Colonial 

 Museum.) 



Ai'iinthochite* fr/dacna RocHEBR., in Bull. Soc. Philomathique de 

 Paris, 1880-'81,p. 121. 



This is evidently a form allied to A. violaceus and A. cottutn*. 

 The seven anterior ribs mentioned evidently include the sutural 

 margins, the number five being constant in this group. 



Genus KATHAKINA Gray, 1847. 



Katharina GRAY, P. Z. S. 1847, p. 65. Type C. tunicatus Wood. 

 CPR. in DALL, Proc. U. S. Mus. 1878, p. 312. 



Valves two-thirds covered by the expanded girdle, the exposed 

 portion divided into dorsal and side areas, instead of central and 

 lateral. Insertion plates sharp, extremely long, thrown forward ; 

 that of the head valve with 7-8 slits ; sinus deep, spongy. Tail valve 

 with a wide caudal eraargination or sinus, and several slits, often 

 partly obsolete, on each side. Girdle broad, smooth, poreless, 

 leathery. Gills extending the whole length of the foot. 



The poreless girdle, the long (ambient) gills, and the abnormally 

 large number and irregularly placed slits of the head valve, all 

 separate this well-founded genus from related groups. The irre- 

 gularly placed anterior slits it shares with Amicula and Oryptockiton. 

 The long gills are also a character of the last-named genus; but in 

 the multifissate posterior insertion-plate and the naked girdle it 

 resembles Crypto conchus and Loboplax. There is but one species 

 known. 



K. TUXICATA Wood. PL 1, figs. 1-11. 



Shell oblong,. elevated, the valves mainly covered by the hhn-k, 

 leathery girdle, a small cordate or flask shaped area of a dark brown 

 color, remaining exposed. 



The exposed portion is about one-third the entire width of tin- 

 valve; it is broad behind, and often hollowed out by erosion : nar- 

 rowing in front like the neck of a flask. The surface when not 

 eroded shows a distinct, smooth and shining dorsal band, the 



