110 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



Aldus {=SiUqua) rostratus Dunker, 1861, figured by Sowerby, Oonoh. 

 Icon., 1874, is said to be from the Arctic Oceau, but this is certainly 

 erroneous. Solen radiatus Linnaeus, appears in Pfeiffer's list of Cuban 

 shells,^ but the shell intended was very likely Tagelus divisus Spengler. 

 No species of Siliqua is known from Cuba. 



Krebs cites Machcera lucida "G-ould," from Morch's Yoldi catalogue, 

 as Central American; but this is doubtless M. lucida of Conrad, from 

 the Pacific coast of Central America. 



There is no large species of Unsis on the west coast of America corre- 

 sponding to the -E/. magnus and U. directus of the northern Atlantic, 

 though the E. calif ornicus is the exact analogue of the Eurojjeau E. ensis 

 and the east American E. minor. Among the Siliquas on the two sides 

 of the continent S. alta and 8. squama, S. media and S. costata, are 

 respectively analogous, while S. lucida finds its counterpart in the 

 S. pulchra of Japan. 



SOLEN MEXICANUS, new species. 



Shell small, straight, parallel-sided, with anterior beaks, the anterior 

 end obliquely truncate; the posterior end squarely truncate with the 

 corners slightly rounded off; hinge with the teeth normal, the ligament 

 unusually long in a very narrow groove; shell white, covered with a 

 polished olivaceous epidermis, longitudinally striate near the ventral 

 edges of the valves. Length of shell, 60 mm.; of ligament, 11 mm.; 

 width of valves, 8.5 mm. ; diameter, 5.5 mm. 



Type.— No. 120634, U.S.N.M. Specimen from the Gulf of Tehuan- 

 tepec. 



This species recalls the Solen linearis of Chemnitz, which, however, 

 is considerably longer in proportion to its width. 



ENSIS CALIFORNICUS, new species. 



Shell small, slender, arcuate, the sides nearly parallel, the valves being 

 slightly attenuated toward the ends, beaks anterior, the anterior trun- 

 cation bluntly rounded, the posterior similar; color white with livid 

 pink streaks concentrically disposed; epidermis olivaceous brilliantly 

 polished; hinge with small and very delicate cardinals (usually broken 

 off), one in the right and two in the left valve, the dorsal ridge compara- 

 tively strong and elevated, shorter than the ligament. Length of shell, 

 00 mm.; of dorsal tooth or ridge, 5.2 mm,; of ligament, 9 mm.; width 

 of shell, 7 mm. ; perpendicular to the chord of the arc formed by the 

 dorsal -margin of the valves, 2 mm. 



Type.— No. 158891, U.S.E.M. Specimen from 14 fathoms sand, off the 

 island of San Pedro Martir, Gulf of California. Some specimens reach 

 a length of 85 mm. 



This species recalls small specimens of the east American E. minor, 

 which, however, differs by being wider distally than in front, larger 

 when adult, with proportionately wider and more arcuate valves. 



' Arcliir fiir Naturgescliichte, 1840, p. 261. 



