1/8 MALACOZOA. GASTEROPODA. SCUTIBRANCKIATA. 



anterior margin ; muscular impression forming three- 

 fourths of a circle. 



1. Emarginula Fissiira. Common Slit-Limpet. 



Shell conical, somewhat compressed, with the aperture oval, 

 narrow hefore ; a vertical median slit extending from its an- 

 terior part to a third of its height ; with an external groove, 

 and corresponding internal ridge to the apex, which is 

 pointed, placed behind the middle, and curved a little hack- 

 ward ; the anterior median outline convex, the posterior con- 

 cave below the point, afterwards nearly straight; from the 

 apex to the margin about forty prominent, narrow, but convex 

 ribs, cancellated by scalar concentric laminae, at the intersec- 

 tions of which the radiating ribs are nodose ; tbe margin cre- 

 nated, having a notch at each of the ribs ; the colour yellow- 

 ish-white. Length of the aperture four-twelfths and three- 

 fourths, height four-twelfths. 



The above description from dead and partially damaged 

 shells ; one found on the Buchan coast in the middle of Sep- 

 tember, 1834; the other brought up from deep water off' 

 Aberdeen, and found by Mr. Leslie, on the 27th of that 

 month. When recent, it is said by Montagu, to be brown ex- 

 ternally, glossy and flesh-coloured within. 



Patella Fissura. Linn. Syst. Nat. 1261. Patella Fissura. Penn. 

 Brit. Zool. iv. 144. PI. 90." f. 161. Patella Fissura. Mont. Test. 

 Brit. 490. Emarginula Fissura. Lamk. Syst. vi. 2. 5. Ed. 2. viu 

 582. Emargiuula Fissura. Flem. Brit. Anim. 365. 



GENUS 3. RIMULA. CHINK-LIMPET. 



Shell conical, with the aperture oval or elliptical and 

 wide, the summit inclined backward ; a vertical slit an- 

 terior to the summit, opening internally by a roundish 

 semimarginate aperture half-way down the anterior side. 



This genus differs from Emarginula only in having the 

 slit toward the summit instead of being at the margin. 



1. Rimula Flemingn. Fleming's Chink- Limpet. 

 Shell conical, compressed, with the aperture oval, narrower 

 before ; the apex recurvate, pointed, and adherent ; a canal 

 of a somewhat triangular form commencing internally, half- 

 way up the anterior medial line, and opening externally in a 

 vertical slit, gradually narrowed, near the apex, and having a 

 groove from it extending to almost the extreme point ; from 



