202 
2. A Monograph or Macrochisma, a genus of Gasteropo- 
dous Mollusca belonging to the family Fissurel- 
lid.e. By Arthur Adams, B.N., F.L.S. 
Macrochisma, Swains on. 
Animal ? Shell elongated, clypeiform, radiately ribbed, extremities 
elevated; foramen very large, elongated, placed near the bind part, 
with a groove posteriorly; the hind margin sinuated. 
1. Macrochisma maxima, A. Adams. 31. testa oblongd, costis 
parum elevatis subrugosis, striisque concentricis obsoletis ornatd, 
fusco radiatim maculatd, dorso elevatd , lateribus planulatis, 
extremitate anticd rotundatd', posticd elevatd , subtruncata; 
foramen dilatatum, postice excavatum. 
Rob. -? 
2. Macrochisma dilatata, A. Adams. M. testa ovato-oblongd , 
radiatim costatd, rubra, albo variegatd , utrinque rotund at a, 
lateribus dilatatis ; foramen oblongum, in medio angustatum. 
Hob. -■? 
3. Macrochisma hiatula, Swainson, Manual of Malacology, 
p. 356. 
Fissurella macrochisma. Sow. 
31. testa ovato-oblongd, radiatim costellatd, fused, subdepressd, 
lateribus concavis, utrinque rotundatd; foramen magnum, ob¬ 
longum, postice dilatatum, extremitate posticd valde elevatd; 
margine vix sinuato. 
Hab. --? 
4. Macrochisma compressa, A. Adams. M. testd anguste 
oblongd, albidd, roseo radiatim pictd, costellis granulosis striis¬ 
que concentricis decussatd, utrinque rotundatd, dorso convexd , 
lateribus compressis, in medio inflexis, extremitate posticd valde 
elevatd; foramen magnum, lanceolatum, postice dilatatum. 
Hab. --? 
5. Macrochisma megatrema, A. Adams. 31. testd ovato-ob¬ 
longd, albidd, roseo radiatim pictd, costellis rugosis striisque 
concentricis sculptd, dorso subelevatd, lateribus planulatis; 
foramen ovato-lanceolatum, permagnum. 
Hab. - -? 
6. Macrochisma cuspidata, A. Adams. 31. testd ovato-ob¬ 
longd, antice angustatd, productd, acuminata, postice elevatd, 
rotundatd, margine valde undulatd, fuscatd, annulis fuscis con¬ 
centricis ornatd, lineis elevatis et concentricis cancellatd, circa 
foramen pallida, extremitate posticd valde elevatd; foramen 
magnum , cuspidatum, postice dilatatum. 
Hab. Cagayan, in insulis Philippinis ; II. C. (Mus. Cuming.) 
7. Macrochisma froducta, A. Adams. 31. testd angusto- 
