FAMILY 1. FISSURACEA. 23 
the breathing apparatus varies between that in the Fissurelle and that in 
the Parmophori ; their shells are therefore sinuated or perforated some- 
times at the anterior margin, sometimes higher up in the bend of the 
shell. The latter division of Emarginule has been set apart by Defrance 
under the new title of Rimula, changed, we believe, by Gray to that of 
Diodora ; this variation, however, is unimportant. 
The shell of Emarginula may be described as being small, shaped 
either like a cone, or very depressed patelleeform cone; it is generally 
radiated on the outside, the rays diverging, as in most cases, from the 
vertex to the basal margin; the margin is generally crenulated, and 
emarginated anteriorly with a small sinus or fissure ; the fissure in some 
instances approaches to the vertex, which is somewhat recurved in a 
posterior direction. 
Ezamples. 
Pl. CXL. Fig. 1. 
Emareinuta Panurensis, Quoy, Voy. de l’Astrolabe, Pl. 68. f. 7 and 8. 
Pl. CXL. Fig. 2. 
EMARGINULA CANCELLATA, Philippi, Moll. Siciliz, pl. 7. f. 15. 
Patella crystallina, Wood. 
Pl. CXL. Fig. 3. 
EMARGINULA NoTaTA, Sowerby MSS. 
Patella notata, Linneus. Chemnitz, Conch., vol. x. p. 324. Vign. 25. 
f; C2 Di 
Pl. CXL. Fig. 4. 
EMARGINULA EMARGINATA, De Blainville, Manuel de Malac., pl. 48. f. 2. 
Pl. CXL. Fig. 5 and 6. 
EMARGINULA TRICosTATA, Sowerby, Genera of Shells, No. 34. f. 6. 
Pl. CXL. Fig. 7. 
EmarGINULA conorpEA, Nobis, Proceedings Zool. Soc,, 1842. 
