378 MEXICAN BO UXDARY SHELLS— DALL. 



Ranella californica, Hinds. San Clemente. 



Sanyuinolaria vitttallii, Conrad. LaJolla. 



Saxldomus aratiis, Gould. La Jolla, 



Scitrria (Lotiia) glgantea, Gray. La Jolla, Guadalupe Lsland, San Clemente, 

 etc. Some of these specimens, especially from the islands, were of remark- 

 ably largo size. 



Semele jyuJchra, Sowerby. Ocean Heach. 



Semele rnhropicfa, Dall. Ocean Beach. 



Semele rujyinni, Sowerby. La .lolla. 



Se2)iife7- hifurcaiiis, Conrad. La Jolla. 



Tapes staminea, Conrad. La Jolla. 



Tellina Ixuhgeims, Hinds. La Jolla. 



Terihratalia transversa, Sowerby, var. caurina, Gould. Ocean Beach. 



Tirela crassaiell aides, Conrad. Mouth of the Colorado River and also on the 

 Pacific. Fresh specimens of this species were found near Tucson, where 

 they had probably been brought by Indians who use marine shells in 

 some of their religious rites. 



Tresus nHttallH, Conrad. Ocean Beach. 



Turrifella f/oniostoma, Valenciennes. Ensenada. 



It may be noted that marine shells in a subfossil but rather fresh 

 condition, sometimes even containing the ligament, occur toward the 

 edge of the lowlands until the ranges east of Tucson, Arizona, are 

 reached. These are probably Post-Pliocene and evidences of the east- 

 ward extension of the sea, which, at a comparatively recent geological 

 epoch, almost insulated Mexico from the continent north of it. A discus- 

 sion of the points involved has been omitted, as they will be discussed 

 by Dr. Mearns in his report on the natural history work. Among the 

 species recognized were SoUnosteir a pallida^ Broderip, Polynices {Xeve- 

 rit<() recluziana, Reeve, MiUinia coloradoensis, Dall, and Tivela crassa- 

 telloides, Conrad. 



EXPLANATION OF PLATES.» 



Plate XXXI. 



Fig. 1. Holospira (Haploatemvia) mearnsii, Dall; 14^.5 mm. ; with profile of aperture; 

 p. 350. 



2. IIolo82)ira{Metastoma) crossei, Dall; 11mm.; with profile of aperture; p. 348. 



3. Holospira (Distomospira) bilamellata, Dall; 20.5 mm.; profile of aperture; 



p. 349. 



4. Holospira (Metastoma) pasonis, Dall ; 23 mm. ; p. 348. 



5. The same in profile. 



6. Jaw of Bulimuhts (Leptohyrsua) artemesia, Bioney; greatly magnified; from 



camera lucida drawing by W. H. Dall; pp. 360, 362. 



7. Epiphragmophora hacMtana, Dall; front view of a rather depressed speci- 



men; 26.5 mm.; p. 339. 



8. Javi^ of Bi(UmuIits (Plicohtmna) rameniosus, CooYter; greatly magnified ; from 



a camera lucida sketch by W. H. Dall; p. 363. 



9. ByfhineUa 2)alomasciisis, Pilsbry; 2.75 mm.; p. 369. 



10. Epipliragmophora hachitana, Dall; basal view; major diameter, 26.5 mm.; 



p. .339. 



11. Epiphragmophora arizonensis, Dall; front view; 17 mm.; p. 337. 



12. The same, basal A'iew. 



' The actual length in millimeters of the specimen figured follows the reference 

 in each case. 



