PALEONTOLOGY ZORRITOS FORMATION 61 



under the upper rib which simulates a suture. Synthesis of 

 three fragments gives the following measurements : Length 

 (163/2 whorls) 90 mm.; diameter at base, 17 mm.; diameter 

 at posterior extremity, 3.5 mm. 



The species erroneously referred to this name by Gabb 

 (loc. cit.) has been properly differentiated by Brown and 

 Pilsbry (loc. cit.) as T. sapotensis. Comparison of Gabb's 

 figure with the photograph of the same specimen given by 

 Brown and Pilsbry shows how far some of Gabb's figures 

 may be trusted. Grzybowski (loc. cit.) referred a specie,; 

 from Caleta Grau to T. altilira, basing his decision, appar- 

 ently, on Gabb's work, and quoting him only in synonymy 

 Grzybowski's figure has the appearance of being less trust- 

 worthy than that of Gabb, if his specimens agreed at all with 

 Gabb's figure, and it is doubtful that he had the same form. 

 It is difficult to place Grzybowski's species ; his figure indi- 

 cates roughly that it is probably of .the altilira group, but if 

 even the broad lines are correctly depicted it is neither 

 altilira nor sapotensis. It is highly probable that it is closest, 

 possibly equal to T. dicingula Woodring (Ms), from the 

 Bowden Miocene of Jamaica; the figure corresponds more 

 nearly to the specimens from Bowden than to any other 

 seen by the writer. 



Turritella guppyi Cossmann (=T. tornata Guppy 54 ) is 

 similar, but has a line above the upper rib which is not 

 present in altilira, and has two rows of granules between 

 the ribs, whereas altilira has three or more. Brown and 

 Pilsbry (loc. cit.) have noted that the interstitial sculpture 

 of guppyi is much less prominent. The specimens of guppyi 

 from Bowden are more delicate than those of altilira from 

 Peru. 



Turritella dicingula Woodring (Ms) from the Bowden 

 beds of Jamaica, is also related, but varies more widely than 



54 Quart. Jour. Geol. Soc. Lond., vol. 22, p. 580, pi. 26, fig. 12, 

 1866. 



