1804. PROCEEDINGS OF TUE NATIONAL MUSEUM. 717 



Geuiis HEMITHYKIS, Orhigny. 



HEMITHYRIS BEECHElil, new species. 



Plate XXXI, tigs. 1, 2, 3, 4. 



Shell nearly white, smooth, marked only by faint lines of growth, 

 much inflated, wide, short, with a very deep wide median sinus in the 

 front margin of the brachial valve and a corresponding projection of 

 the pedicle valve; brachial valve with a much incurved apex and no 

 median septum, though in an old specimen the deposit of shelly matter 

 between the muscular impressions may give rise to an obscure promi- 

 nence simulating a septum; teetli strong, the sockets long, deep, d.ee[)ly 

 transversely grooved, crural plates excavated, divided to the apex in 

 the medial line; heightof brachial valve, 15.5 to 16; width, 1G.5 to 19 mm. 

 The depth of this valve is about 12 mm. 



Station 3473, in 313 fathoms off Honolulu, Hawaiian Islands. No. 

 107009, U.S.N.M. 



Although only three brachial Valves and some fragments of this 

 species were collected, from which the slender crural processes were 

 broken, there is no doubt that the material represents a new species. 

 The only species with which it need be compared is H. lucidaj Gould, 

 which is a relatively much narrower, more compressed, and less tlexuous 

 shell of a very much smaller size. It is Japanese in habitat, as far as 

 yet known, and is peculiar in having, normally, the foramen completely 

 closed below by deltidial plates. Judging by the lines of growth, which 

 agree on all the specimens, the proportional width of E. Beeclieri is 

 quite as great in the young as in the adult, but the young of the size 

 of adult H. lucida would exhibit no mesial flexure worth mentioning. 



The species is named in honor of Prof Charles E. Beecher, of Yale 

 University, whose contributions to our knowledge of brachiopoda are 

 well known. 



HEMITHYRIS CRANEANA, new species. 



Plate XXXI, tigs. 5, 6. 



Shell small, translucent gray, very thin, with a flexuous anterior 

 margin and almost smooth surface; lines of growth faintly indicated 

 and by close inspection with a lens occasional irregular, radiating, very 

 slightly elevated markings (such as occur more or less on all shells 

 usually called smooth) may be discerned on the polished surface; pedicle 

 valve pointed above, with the sides slightly rounded and the basal 

 margin slightly concave; this valve is rather more inflated than the 

 brachial valve, but not extremely so; foramen subtriangular, wide 

 below, the deltidial lamelhie obsolete; teeth small, very short, cross- 

 striated, and close to the foramen; cavity of the valve smooth; the 

 muscular impressions have left no trace, but they are crowded close up 

 under the foramen; there is no indication of a septum. Brachial valve 

 rounded-triangular, the basal margin gently, evenly arched upward; 

 a feeble mesial septum about one-third as long as the valve separates 



