i'io Miscetlanehits, 



leave ttiem ill the group of the Hirudines in which they had been 

 placed. The other new characters, observed by M. Blan chard, confirm 

 this opinion, and appear to show that the MalacobdellcB should con- 

 stitute a particular division, completely independent of the AnnelideSs 

 the Hirudines, and the Anevormesi {Trematodes planar is) . — Comptes 



Monograph of the recent species q/'Trigonia, including the descrip- 

 tion of a new species from the Collection of H, Cmning, Esq. By 

 .^^THUR Adams, R.N., F.L.S. &(j*i ov/ lodnm'/i his&'iiq mo iil 



>{i..f!i)': ..,i.i;;..a 1;; : m T. i>r i^iiuifiiW.v^il odlbnai-iisldfii 



r '(• IRIGONIA, Bruffuiere. , t , j.. +r.rr+ +o 



'Testa cequivalvisy incBquilateraliSy transversa^ tr(§tond^ mtArc^mi' 

 y^cfy.^uborbicnlaris ; denies cardinales oblongi, later aliter com- 

 9£|j ^re*52, divaricati; duo in valvd alterd, utroque latere trans- 

 'om-.'^crsim sulcati ; quatuor hi alterd, uno tantum latere sidcati ; 

 nrii! Hgcirnentum e^t^s^nijCrassum, marginale ; impressioaesmws&u*^ 

 .^,(j; lares duce. ■ -i.l-, iuujn ..ii^noqmi iffi 



' Shell equivalve, mostly inequilateral, transverse, rather tri^'figulai^ 

 sometimes suborbicular ; cardinal teeth oblong, laterally compresse%> 

 divaricated, two in one valve transversety grooved on both sides, four 

 in the other grooved on one side only ; ligament external, thick, rather 

 short, marginal ; muscular impressions two, distinct, lateral ; palleal 

 impression very nearly entire. 



Trigonia margaritacea, Lamarck. T. testd suborbiculaidy 

 radiatim costatd, intus margaritaced, costis elevatis, verrucosli^^ 

 ^•^' subasperis ; margine plicato. ' '""' '* ' '^^ 



Shell rather compressed, with 20 or 23 rath^f narrow, nodulosi^," 

 radiating ribs ; the hinder ribs very compressed, all excepting the 

 front ribs wide apart. -- ^ ^ 



Hab. Van Diemen's Land; Ronald Gunn, Esq. (Mus. .Cfiiiriiy''^^^' 

 Trigonia margaritacea, Lamar cJc^ Ann. du Mus. tomi"iVi''ii(i I^B\ 

 pi. 67. fig. 2. ^ -^ "^''^^^ ^V^^'^- 



T. pectinata, Lamk. -'^ -'- i" V"'^'^^^*^ ^^^'^'^'P ^ §"^1^1 



hrt, T n Ji ;jiOB[jijubi>Lifiiol. /life >o ' Simon 



Trigonia Lamarckii, Gray. T. testa suovenincosa^ solidcj^;. 

 costis 20-26 angustatis planiusculis nodidosis radiantibu^.^ 

 V. costis arece posticce confer tis '^^^^*^*^«^*f»-^^^«if^*^<*.»4^?%^,(i9^ferq 

 '"';j:is nodulosis. X'Lf^viXZr^ .^F , t^^^oloni 



Hab. m Nova HoUandia. ,.,j^ 



Shell rather ventricose, solid, with 20 to 26 narrow, flat-topped,,, 

 nodulose radiating ribs ; the ribs of the hinder slope narrow, rather 

 crowded ; ribs convex, all close together and nodulose. 



Hab. New Holland, Port Jackson ; Mr. Stutchburg. (Mus. Cum.) 

 Varies, with the inside white, salmon-coloured, yellow, or purple 

 bronze. .^^ 



Trigonia Lamarckii, Gray, Annals of Nat. Hist. 1838, p. 482. ,(f 



Trigonia Jukesii, A. Adams, n. sp. T. testd ovato-trigond, 



