13 



incurvatis; pube pland ; dentibus lateraUbus approximatis . Long. 

 1-30; lat. 1-60 pol. 

 Hab. Tumbez, Peru (Guming). 



Closely resembling dentiferus, but not provided with the charac- 

 teristic tooth, much stronger and more triangular, and with its ven- 

 tral edge more arcuated, and its front extremity more attenuated. 

 The front dorsal edge appears retuse (which it is not in reality), from 

 the lateral projection of the swollen beaks. The lower margin is 

 stained with violet anteriorly. 



DoNAX NAVicuLA. Don. testd elongato-trigond, crassd, subventri- 

 cosd, nitidd, subin(equilaterali, siiblcevigatd (stfiis radiantibus 

 tantum in medio perspicuis), albd, epidermide flavd indutd, prope 

 marginėm dorsalem utringue brunneopurpurascente strigatd; mar- 

 gine ventrali in medio ventricoso, intus crenato ; dorsali antice 

 subrecto et subdedivi, postice incurvato et declivi ; ared posticd 

 lavi, subconcavd ; latere antico longiore, angustato, ad extremitatem 

 rotundato ; postico cuneiformi, ad extremitatem obtuso ; ligamento 

 minimo ; costd umbonali obtusd ; superficie internd albidd, utringue 

 superne purpured ; dentibus lateraUbus maxime approximatis. 

 Long. 0-40 ; lat. 090 poli. 



Hab. Gulf of Nicoya, Central America (Cuming). 



Allied to CuUforniensis, but more triangular. 



DoNAx GRACiLis. DoH. testd elongatd, angustd, nitidd, valde in- 

 eeguilaterali, compressd, sublcevigatd, albidd aut pallide viulaceo- 

 rufescente, epidermide lutescente indtitd ; margine ventrali convexo 

 aut subarcuato, haud flexuoso, intus crenulato ; dorsali magis mi- 

 nusve livido, utringue subrecto, antice vix paiilu/um declivi, posticd 

 valde declivi; latere ant'co pradučio, atienuato, ad extremitatem 

 rotundato, postico acuminato -cuneiformi ; ligamento minimo ; ared 

 pcsticd Icevi, obtusissimd ; costd umbonali obtusd ; superficie internd 

 purpurascente ; dentibus lateraUbus perspicuis, approximatis. 



Var. b. Testd albidd, radiis paucis Uvido-rufescentibus ornatd. 



Var. c. Testd rufescente aut lividd. 



Long. 0-40 ; lat. 1 poli. 



Hab. Bay of Guayaąuil. Var. b. Chiriqui. Var. c. Bay of Carac- 

 cas (Cuming). 



Allied to Owenii, but with the margin crenulated. 



DoNAX soRDiDus. Don. testd abbreviato-cunciformi, convexd, niti- 

 diusculd, solidd, valde inaguilaterali, striis exiUbus simpUcibus 

 confertim radiatu, sordide albidd ; lineis elevatis obliguis subcon- 

 centricis, partem superiorem et Irevigatam testą postice asperanti- 

 bus ; margine ventrali crenulato, medio arcuato ; dorsali antico, 

 declivi et subrecto ; postico subrecto et valde declivi ; latere antico 

 attenuato ; postico brevi et infertie {in adultis etiam superne) obtuse 

 angulato ; pube fortiter et confertim rugis subdecussatis concentrice 

 exaratd ; costd umbonali subangulatd ; superficie internd albidd, 

 purpureo infectd ; dentibus lateraUbus approximatis, antico per- 

 magno. Long. 0'70; lat. 1 poli. 



Hab. Cape of Good Hope. Mus. Brit., Cuming. 



