646 LOWER CALIFORNIAN BULIMULTJS DALL. 



Section ORTHOTOMIUM. Cn.ssr jiini Fisilicr. 

 Bulimulus ( Orthotomium ) sufflatus Gould. (/>'. vedvalis Gld. olim.) 



Lower California, M'u'Ai; low lands abont La Paz, Gabb; San Jose 

 del Cabo to La Paz, Bryant. Sierra Lagnna to 3,000 feet above the sea, 

 Eisen. Variety insularis ( 'ooper, Espiritu Santo Tsliind, P)ry;ni( . Abnn- 

 dant near La Paz, Belding. (Plate lxxii, Fig. 0.) 

 ^ This characteristic shell has no coloration except in its ('i)i(l('rniis, 

 which is straw color or jjale olive, intensilied at lines whicli represent 

 resting stages, and more or less polished. The form varies from 33.5 

 by J 7, and 30.5 by L*l to 32 by 23 mm. The peristome is slightly re- 

 tlected in front and widely over the nmbilicns; elsewhere it is not 

 retlected. In specimens whicli have survived a dry season attached to 

 bark or a stone, the inside of the i)eristome and the space on the body 

 between the two li])s is often much thickened by a deposit of callus. 

 The nucleus is similar to that of Lcptohj/rsiis, except that the ai)ical 

 part is irregularly punctate, and the riblets instead of being even and 

 sharply defined are more or less wavy and on the shoulder and earlier 

 part give a vermicular effect. The apical pit is not conspicu(ms though 

 evident in some examples. Pathologic specimens showing lumps or 

 tubercles on the pillar are not very rare, but normally the pillar is 

 simple. The young are frequently taken for B.pUnJa from which they 

 may be discriminated by their projecting and uKU-e sharply sculptured 

 nuclear whoils and less open umbilicus as well as more ovate form. 



Bulimulus (Orthotomium?) pilula W. <;. Binuey. 



Cape St. Lucas to Margarita Island, Xaiitus. San Jose <lel Cabo, 

 P>ryant. The spe<'imens collected at Punta Arena by Bryant and men- 

 tioned by Dr. Coo[)er are i)rol)ably immature .s7c_^af«.s'. (Plate i.xxii, 

 Fig. 10.) 



The types of this s])ecies in the National Museum have a distinct and 

 mature appearance. The specimens connecting them with sn(flattts are 

 usually young sufflatus. Tlie two types have 4 and 4i whorls, respec- 

 tively, as many as s])ecimens of sufflatus four times their size. The 

 nuclear whorls arc smaller than in sufflatus and more delicately sculp- 

 tured, while the incremental wrinkling <hi the body whorl is more 

 conspicuous and regular than in the larger species. I have seen no 

 specimens of pilula Avhich appear to be genuine except the types. All 

 the others wlien critically studied resolve themselves into varieties of 

 sufflatus. 



IT. S. NA'i'KtXAL MrsKiM. ./?n<r, IS9:)\ 



EXPLANATION OE ELATE LXXI. 



Page. 



Ei<;. 1. Hill 'nil til Kn liaiUijl Dall <'10 



L'. liiiliiniiliix Ziledoiii Hall <>Tl 



3. BitUmahis Jirjiaiiti {Coo\n'r) Dall, from l)ciiiiul. sliowiiig- iiitt'iiial la- 



mella through an openinji- made into the \vhorl (>!.'> 



4. liitlimulus reseyiatiuH Dall <)!;") 



5. liiiUmitlun T'l'ficjiiaiius Dall, IVom behind, tlio whorl ojx'ned to show th«' 



otlu-rwise invisible lamella 645 



