400 MOLLUSCA. 
a shell, labelled “ Guatemala (A. Morelet, H. Cuming) .”’ which agrees very well with 
the above-quoted description and figure; it closely resembles P. wyldi. The 
measurements given by Clessin in the description, 14 and 7 millim., are exactly 
those of his lower figure; but this is magnified to 3, according to the line which 
indicates the natural size. 
Planorbis edentulus, Clessin, loc. cit. p. 220, t. 33. fig. 2: diam. 6°5, alt. 1°5 millim.; 
whorls 4. This species is said to belong to the group of P. armigerus, 1. e. to 
Planorbulina, but to be without internal lamelle. It differs from P. dentiens, 
var. edentula, F. & Cr., in the number of whorls, and from P. obstructus (which 
agrees in this respect with Clessin’s species) in the absence of internal lamelle ; 
but neither Fischer and Crosse nor I have seen full-grown specimens of the latter 
without internal lamella.—‘ Central America.” 
Planorbis circularis, Clessin, loc. cit. p. 221, t. 33. fig. 3: diam. 7, alt. 2 millim. This 
species agrees in most respects with P. petenensis, Morelet ; but differs from it in 
the more arcuate right and left margins of the aperture, which render its form 
nearly circular. The number of whorls is stated to be 6 in the text, but on the 
figure 4 only are to be seen. The specimen in Clessin’s collection is marked 
“ Antillen,” and its whorls are somewhat more gradually increasing.—‘* ? Central 
America.” 
Planorbis strictus, Clessin, loc. cit. p. 223, t. 33. fig. 4: diam. 6, alt. 1:7 millim. ; 
whorls 4. This form agrees very well with specimens of P. stagnicola, Morelet, 
from Cuba, given by J. Gundlach to the Berlin Museum.—* ? Central America.” 
Planorbis solidulus, Clessin, loc. cit. p. 224, t. 33. fig. 10: diam. 12, alt. 3:5 millim. ; 
whorls 5. The specimens of this species in Clessin’s collection, kindly communi- 
cated by the author, are characterized by a very distinct turning to the left of the 
last whorl near the aperture (underside), in which respect it resembles P. pronus 
and P. subpronus; but in the original description and figures this character is not 
noticed.— Locality unknown. | 
Planorbis mexicanus (Philippi), Dunker, in Martini & Chemnitz, Syst. Conch.-Cab. 
ed. 2, Limneaceen, t. 12. figg. 1-3 (sine descr.). Perhaps a very young specimen 
of P. caribeus.—Mexico. 
ANCYLUS. 
Ancylus, Geoffroy, Traité Coq. Terr. et Fluv. de Paris, p. 122 (1767) ; O. Fr. Miller, Hist. Verm. 
ii. p. 159, &. 
Shell simply conical, without spiral whorls; apex pointed, recurved backwards, 
usually somewhat asymmetrical ; aperture occupying the whole length and breadth of 
the shell. 
Feelers short, blunt. 
