UNIO. 507 
Unio rugulosus, Charp., although said to be Australian, is so very like U. dysoni 
that I strongly suspect the two are identical, although I have not seen a specimen. 
U. rugulosus is mentioned in E. Smith’s valuable paper on the Australian freshwater 
shells [Journ. Linn. Soc., Zool. xvi. p. 312 (1882)], but no additional information is 
given respecting it. 
* 31. Unio macnieli. 
Unio macnielii, Lea, Proc, Acad. Phil. 1869, p. 124’; Journ. Acad. Phil. (2) viii. p. 25, t. 8. 
fig. 22°; Obs. Gen. Unio, xiii. p. 29, t. 8. fig. 22°. 
Hab. Nicaracva: Rio Gigillillo, Corcuera (McNiel 1-3), 
* 32. Unio yzabalensis. (Tab. XXXIX. figg. 9-lla.) 
Unio yzabalensis, Crosse & Fisch. Journ. de Conch. xl. p. 296 (1892)! ; Miss. Scient. Mex., Moll. 
il. p. 597, t. 64. fige. 4, 4a, b?. 
? Unio scamnatus (Morelet), Lea, Obs. Gen. Unio, vii. p. 77°. 
Testa rhomboidea, paulum et equaliter convexa, liris concentricis inequalibus confertis, nonnullis bifurcatis 
vel anastomosantibus sculpta, ferrugineo-fusca, antice sat producta, modice arcuata, supra levius arcuata, 
infra magis ascendens, verticibus in 2~4 longitudinis sitis, margine dorsali postico valde arcuato, margine 
postico subtruncato, margine ventrali antice valde ascendente, medio subrecto vel subsinuato ; dentes 
cardinales sat validi, subtriangulares, sulcati, secundus valve sinistre minor; facies interna pallide 
purpurea vel albida. 
a. Long. 62; alt. vert. 38, ale 35, diam. 233 millim, Vertices in 2 long. 
ee ee ees ee 4b Ey 
C. 99° 453 ; 99 28, 9) 26, 99 153 9 99 3 99 
at, 4a; 9 26, ,, 244, ,, 18 ” " go 4s 
Ge be 48 5 99 27, 99 27, 99 16 99 99 3 9 
a, ¢, d, ¢. Specimens from Panzos; 6. From Fischer and Crosse’s description and figure. 
Hab. GuatemMata: Panzos, in the Polochic valley (Conradt) ; Lake Yzabal (Bocourt * 2). 
Honpuras: Comayagua (Leconte ®). 
I have given a fresh diagnosis of this species, as among the specimens collected by 
Conradt there are some of much larger size than the type described by Fischer and 
Crosse. U. yzabalensis is so near the Cuban U. scamnatus, Morelet *, that I think it 
very probable that U. scamnatus, Lea *, from Honduras, may belong to the present 
* Unio scamnatus, Morelet, and U. gundlachi, Dunker, both from Cuba, are treated as one species by 
Lea (Joc. cit.), but they are separated as distinct by Dunker (Malak. Blatt. v. pp. 228, 229) and by Arango 
(Contribucion Faun. Mal. de Cuba, p. 144). As there is some confusion regarding these Cuban forms, I have 
re-characterized them, after having compared the specimens in the late Dunker’s collection, now in the Berlin 
Museum, with Morelet’s description and Sowerby’s figure. 
Unio scamnatus. 
Unio scamnatus, Morelet, Test. Noviss. i. p. 30 (1849). 
Unio gundlachi, Dunker, Malak. Blatt. v. p. 228 (1858). 
Elliptic-oval, sulcated, compressed ; hinder half as high as or higher than the fore half; ventral margin 
64* 
