NO. 2002. DIAGNOSES OF NEW PACIFIC SHELLS— DALL. 595 



end more attenuated, and the beaks almost exactly central. Length 

 21.75; of anterior end 10,75; height 13.0; diameter 10.0 mm. 



South coast of Oahu Island, Hawaiian Islands, in 310 fathoms, 

 sand, bottom temperature 43.5° F. Cat. No. 252329, U.S.N.M. 



LYONSIA PUGETENSIS, new species. 



Shell large, thin, pearly under a thin olivaceous gray periostracum 

 which is covered with fine radial lines to which fine sand adheres 

 strongly, so that an attempt to remove the sand also destroys the 

 greater part of the periostracum ; the shell is slightly inequivalve and 

 very inequilateral, the anterior end being much shorter; the perios- 

 tracum projects over the shelly margin; the anterior end is evenly 

 rounded, the posterior rostrate, the beaks not conspicuous; the base 

 is convexly arcuate in the middle but is rapidly attenuated toward 

 the rostrum, which is terminally truncated; interior pearly, pallial 

 area relatively small within the somewhat irregular unsinuated pallial 

 line; hinge edentulous with a small narrow lithodesma. Length of 

 shell 36; of anterior portion 15; height at beaks 17; maximum diam- 

 eter 10 mm. 



Another specimen is 50 mm. long and 22 mm. high, while a third is 

 52 mm. long and 28 mm. high. 



The type. Cat. No. 249966, U.S.N.M., is from the coast of Wash- 

 ington (H. Hannibal); another is from Chignik Bay, Alaska, in 16 

 fathoms, sand (Dall); and a third from Puget Sound (Kincaid). 



This is the largest Lyonsia of the coast, if we except Entodesma 

 (Agriodesma) saxicola Baird. The smaller specimen was taken as 

 type because of the better condition of the surface, the periostracum 

 in adults being largely dehiscent. 



LYONSIELLA MAGNIFICA, new species. 



Soft parts; siphonal orifices not produced, both profusely papillose 

 and separated externally by a bare space; incurrent siphon with a 

 strongly marked circular valve internally. Gills flat, fleshy, with two 

 laminae completely soldered to the fleshy siphonal septum and with 

 that completely separating the pedal and siphonal chambers; there 

 are no perforations in the septum and no free portions of the gills; 

 foot cylindrical, grooved behind, with a long and profuse byssus of 

 numerous threads; mantle closed except for the narrow byssal fora- 

 men and the siphonal orifices; palps short, soldered to the mantle 

 except behind in front of the foot; mantle margins smooth. The 

 excurrent siphon has a small short valve projecting from its orifice, 

 which when contracted is bilabiate, the fold vertical. The general 

 anatomy recalls that of Lyonsiella abyssicola, in which, however, 

 Pelseneer indicates an excurrent siphonal tube of moderate length. 



Shell thin, inflated, subquadrate, inequilateral, inequivalve, gaping 

 behind; the right valve a little larger than the other; color pearly 



