92 One Thousand Objects 



719. The NUMMULITE (Nummulina planulata). 

 Though ^legant, this species is rare. It has a lens or 

 lentil form and spiral arrangement, smooth, bright- 

 brown, translucent, with radiating septal lines. The only 

 localities named for it are Portsmouth and Scarborough. 

 (PL IX., fig. 1 6.) 



720. RAISED POLYSTOMELLA (Polystomdla crispci). 

 This shell is also of a lens shape and spiral ; the seg- 

 ments or chambers divided by raised lines, with interme- 

 diate elevations and depressions ; in young shells the ex- 

 tremities of the septal ridges are elongated into pointed 

 spines ; the mature shell is opaque and dirty white. 

 Found all round the coast. 



721. DEPRESSED POLYSTOMELLA (Polystomdla umbili- 

 catula). The shell is of a Nautilus form, compressed 

 sideways ; but the septal lines are depressed, and not 

 elevated as in the preceding, and the intermediate furrows 

 are only along one side of each segment ; texture trans- 

 parent. Occurs at Plymouth, Exmouth, Torquay, South- 

 port, Shetland, and other places. (PL IX., fig. 17.) 



722. COMMON ROTALINA (Rotallna' Seccaru). This 

 has the form of a Trochus shell, being convex on one side 

 and flattened on the other ; the chambers are divided by 

 depressions on the surface, the under or flattened side 

 having numerous protuberances, especially near the cen- 

 tre ; semi-transparent. Found on every part of the coast. 



723. OCHRACEOUS ROTALINA (Rotalina ochracea). 

 The rarest of British JRotaliiuz, having only been found at 

 Shetland. The septa of a pale ochre tint, and the seg- 

 ments of a deep brown. (PL IX., fig. 18.) 



724. OBLONG ROTALINA (Rotalina oblongd). This 

 shell has a curious, unequal appearance, being developed 

 broadly on one side of the spiral, then rapidly diminishing. 

 It is a pale olivaceous tint, and semi-transparent. Found 

 at Skye, the Shetlands, Guernsey, and a few other locali- 

 ties. (PL IX., fig. 22.) 



725. ROTALINA (Rotalina concamerata). The form is 

 that of a Trochus shell. It is chiefly found in its young 

 state attached to other bodies, and is then very different 



