OF SAXTO DOMIKGO. 218 



very prominent longitudinal ribs, abont nine to a volution, and very uniform in size, with regularly concave intei-- 

 spaces. These are crossed by small revilving lines, most prominent where they cross the ribs. Aperture broad; 

 inner lip heavily encrusted, the margin of the encrustation rising beyond the surface of the whorl as a stout plate ; 

 internally it is strongly rugose iu advance. Outer lip internally striate in advance. 



It would seem rash to attempt to separate shells so nearly allied as the above four 

 species, were it not that I had in all over 1300 specimens. Of these, the first was 

 represented by 130, the second by about 50, the third by over ()00, and the last by 

 over 500. In not a single instance did I hnd a specimen that I could not assign with 

 certainty to its proper species, so that I feel well convinced of the validity of my 

 determinations. ' . 



The diagnostic ditferences between them may be briefly stated as follows : P. 

 Yeraguensis is evenly sculptured by small, uniform longitudinal ribs, and crossed l)y 

 still smaller hues ; P. costatus has veiy large round ribs of uniform size throughout, 

 crossed by very small lines ; it is also by far the most robust of the foiu', and is the 

 only one that possesses a rugose columella. P. semi-costatus is not markedly unlike 

 P. costa.'ns in the upper whorls, except that the cross sculpture is much stronger, in 

 which last character it excels all the others ; but in the presence of the few varix-like 

 ribs on the body whorls, it is at once distinguishable. And finally, F. Guiypyi can 

 be recognized at a glance by its very slender form, the four, large irregular ribs and 

 the delicate cross lines. The last is much the prettiest species of the four, and I 

 dedicate it to Mr. J. M. Griippy, whose name occurs on almost eveiy page of the 

 present paper. 



NAS8ARIA. Link. 

 HiNDSiA, H. & A. Ad. 



N. brevis. Gabb, n. s. v . . 



Shell short, broadly fusiform ; spire as long as the mouth ; whorls eight, the first nuclear, convex; suture deep; 

 whorls covered by about nine pi'ominent ribs, extending from the suture, and on the last volution ending below the 

 middle. Surface crossed by strong revolving lines with concave interspaces. Aperture broad ; inner lip encrusted 

 and transversely rugose, especially in advance ; outer lip internally striate ; canal short, recurved. Length .8 inch ; 

 width .5 inch. 



ECTRACHELIZA. Gabb, u. gen. 



Shell acuminately oblong, spire elevated (always truncate in the only species known). Surface compressed near 

 the suture ; inner lip encrusted, columella sinuous, short, outer lip produced in advance. 



This genus seems to be allied in many of its characters to Cominella and Trun- 

 caria. Like them it is compressed adjoining the suture. It shows no trace of 

 umbilicus as is seen in most of the Buccinidon) but its most distinctive character is in 

 its obliquely sub-truncated columella, Avhich does not i-each the anterior end of the 

 shell. It differs from Truncaria in having no fold on the coluiue!la, and in the n})er- 

 ture not being emarginate posteriorly. Whether the truncated apex will be of generic 



A p. S. VOL. XV. OB. 



