MAZATLAK UNITALVES 433 



(c.) Ribs continuous over the base. 



534 Chemnitzia tenuilieata, n. s. 



Ch. t. elongatd, angusta, albidd ; vertice niccleoso Jiaud 

 extante, marffinibus spii'ce reef is hmid stiperante ; anfr. (testa 

 juniore) vi., planatis, suturd angustd, distinctd ; lirulis circiter 

 xxiv. rectis, a basi ad apicem ascendentibus, circa basin con- 

 tinuis.; inter stiiiis Uneis curvatis decussatis ; labro acuto, 

 labio tenui, columelld gracili. 



The species is described from a perfect young and a broken 

 adult specimen. The latter, wben complete, must have 

 measured about '23. The young one measures long. '065, long, 

 spir. -045, lat. '027, div. 15" : {t. adultd, 11».) 



Hah. — Mazatlan ; 2 sp. off Spondylus ; L' pool Col. 



Tablet 2005 contains both specimens. 



535. Chemnitzia ttnifasciata, n. s. 



Ch. t. tereti, angustd, Jiavescente, fascia dcnsius coloratd in 

 medio anfractuum sptiram ascendente ; vertice nucleoso helicoideo, 

 satis magno, marginibus sjnrce rectis vix superante, liaud pro^ 

 minente, anfr. ii. subglobosis, verticaliter sitis, apice parum 

 conspicuo ; anfr. normalibus planatis, suturd liaud conspicud ; 

 lirulis minimis rectis, acutis, circiter xx. circa basin prolonga- 

 tam rotumlatam continuis ; striuUs spiraUhus decussanfibus, 

 in spird iv., in hasi crebrioribus ; aperturd elongatd ; columella 

 vix contortd ; labio valido. 



The spiral band of colour can only just be seen in a good 

 light, the shell probably being dead ; but it is the only Mazat- 

 lan species which possesses the character. In some respects it 

 resembles the W. Indian Ch. reticulata, C. B. Ad. .- bixt the 

 upper whirls are much flatter. The only specimen found has 

 5 normal whirls, and measures long. "09, long. spir. "06, 

 lat. -025, div. 18". 



Hah. — Mazatlan ; 1 sp. off Spondylus ; L'pool Col. 



Tablet 2006 contains the specimen. 



Subgenus DUNKERIA. 



Chemnitzia, anfractibus tumidis, decussatis. 



This group combines the characters of Chemnitzia and AcLis, 

 presenting the mouth of the former with the roimded whirls 

 Dec. 1856. oo. 



