46 MOLLUSCA. 



metrical. Anterior border of mantle deeply cleft, in correspondence 

 with which the shell is perforated or provided with a slit on its outer 

 lip. Kidneys paired, that of the left side rudimentary. Auricle 

 paired ; ventricle perforated by rectum. Tongue rliipidoglossal, 

 in that the complicated radula bears in each transverse row, in 

 addition to the median and intermediate plates, a great number of 

 lateral plates which are arranged in a fan-like manner and the upper 

 edges of which are bent into the form of hooks. They are all 

 herbivorous, and are without a retractile proboscis or siphonal tube 

 at the shell aperture. They often possess filiform appendages on 

 the foot. A penis is not developed. 



Fam. Fissurellidae. Shell cup- or cap-shaped, with an aperture at the apex 

 or an anterior marginal excavation for the entrance of water into the mantle 

 cavity, which contains two symmetrical gills. Mantle edge fringed. The 

 animals resemble the Patdlidce, are provided with tentacles and a large foot. 

 Fissurella Brag. Shell with longish aperture through the apex, which is 



placed in front of the middle. 



F. grcBca L., Adriatic and 

 Si ^ffw^ Hfe. Mediterranean. Emarginula 



Lam. An excavation at the 



anterior edge of the deep 



bowl-shaped shell. E. clon- 



f I^^^v^r is_/>~^~mP^i*- f ' ."^irls^^^^r , ~ , . -. . ,. j 



gata Costa, Adriatic and 



Mediterranean. Scutus 

 Montf. ( Pannoplior'us 

 Blainv.) Australia. 



FIG. 620.-0m textili* (regne animal). E, proboscis; Fam. Haliotidse. Sea-ears, 

 Si, siphon ; F, tentacle ; 0, eye. ormers. Shell flat, ear- 



shaped, internal mother-of- 

 pearl lustre, with a row of holes on the left side. The mantle cavity is on 

 the left side and contains two gills, of which the right is the smaller. Foot 

 fringed, with a broad pedal surface. Head with two long tentacles and short 

 stalked eyes. Hallotis L. Spiral of shell small and flat. Foot projecting 

 slightly over the shell. H. tuberovlata L., Adriatic and Mediterranean. 



Sub-order 4. Ctenobranchiata (Anisobranchiata, e.p.). With large 

 cervical gill of pectinate form on the left side with small olfactory 

 organ (so-called rudimentary gill, fig. 516, Nfy. A spiral shell is very 

 generally present (fig. 520). The male possesses a penis on the right 

 side. Most are carnivorous and possess a protrusible proboscis. 



1. Rhipidoglossa. Each transverse row of the radula with 

 numerous lateral plates arranged in a fan-like manner (fig. 514, b). 



Fam. Trochidae, (Top shells). With conical shell and spiral oper- 

 culum. Foot prolonged into cirri and lobes. Eyes on short stalks. Turbo L. 

 With roundish (convex) windings, round aperture, and buccal edge somewhat 

 cut off. T. vncjosiis Lam. Trnclms L. With angular windings, buccal edge 



