﻿2o6 T'sr.rnosPATHA 



i? not entirely straij^Iit. Uonri^uij^nat's Biirtonia contorta i^ 

 probably a specimen of ibis s]iecies wliicli was injured and is 

 on tbat account narrowed anteriorly. Until the shell has made 

 a cr.-nsiderable p^rowth its outline is exactly that of a Jhnngston- 

 cnsis of the same a£]^e. 



PsEiTDosPATiiA sunTRiANCri.AKis ( 1 knumuiynat) . 



v'^hcll trapezoidal, compressed, with a small i^irojectini^ an- 

 terior and a rather high post-dorsal win.q;; the dorsal line 

 nearly straig^ht : the posterior end obliquely truncate, with a 

 low, double posterior ridg'e ; surface with irre£?ular, concentric 

 growth lines, beautiful yellowish-chestnut, and faintly rayed 

 before and behind; pseudocardinals wanting; laterals thick. 



Length 102, heig-ht 49, diam. 18 mm. 



Lake Tanganyika. 

 Burtonia siibtriangiilaris Bourguignat, Un. and Tr. Tan., t886, 



p. 35 ; Icon. Mai. Tan.. 1888, pi. xxv, iig. 2. 

 Pseudospatha subtriangiilaris SI^tPSON, Syn.. tqcx), p. ^yS. 

 Burtonia (^randidieriana Bourguignat, L^n. and Tr. Tan.. 1886, 



p. 42; Icon. Mai. Tan., t888, pi. xxvii. figs. 1-3. 



Pseudospatha bourguignati (Bourguignat). 



Shell irregularly elliptical or obovatc, subsolid, compressed, 

 with a small, projecting anterior and a moderate posterior 

 wing-; dorsal line considerably highest at the middle, from 

 which point it slopes in a straight line forward and back ; out- 

 line from the anterior point around the base to the posterior 

 point nearly evenly curved, a little fuller behind the middle ; 

 beaks compressed ; surface splendid reddish-chestnut, the upper 

 part of the umbonal region violaceous, interior violet and mag- 

 nificently iridescent; pseudocardinals wanting; laterals solid. 



Length 81, height 42, diam. 20 mm. 



Lake Tanganyika. 

 Bitrtonia bourguignati Bourguignat, Un. and Tr. Tan., 1886, 



p. 38; Icon. Mai. Tan.. 1888, pi. xxvii, figs. 4-5. 

 Pseudospatha bourguignati Simpson, Syn., icpo, p. 578. 



