Eolidia papulosa. 377 



processes, which are very numerous, and arranged in close 

 indistinct rows along the. sides, sloping backwards : they are 

 slightly compressed, lengthened, but unequal, those next the 

 foot being the shortest. When examined narrowly, they are 

 seen to be mottled by the configuration of their interior struc- 

 ture ; and, when compressed between plates of glass, it will be 

 found that there is always a transparent circular spot at the 

 apex. Head depressed ; the mouth terminal, subinferior, 

 encircled with a dilatable lip; and furnished with a very short 

 proboscis, which contains a pair of rather large, thin, oval 

 corneous jaws, twisted into a tooth-like process at the apex * ; 

 and between them lies a thick fleshy tongue, compressed 

 laterally, and armed on its outer and upper edge with a series 

 of transverse narrow corneous laminae, finely pectinated on 

 the free margin ; a structure very different from that of the 

 Tritonia or Doris. Tentacula four, conical, nearly equal, 

 very contractile ; the inferior originating at the sides of the 

 mouth ; the superior placed on the back, and annularly 

 wrinkled: from the bases of the inferior a dark line runs 

 backwards to the superior, and forms a triangular mark above 

 the mouth ; but this is often absent. In the centre of the 

 back there is a tumid spot, indicating the position of the 

 heart, the pulsations of which are often very perceptible. 

 Foot white, clear, with a thin rather broad undulating mar- 

 gin, prolonged at the anterior angles into an acute process. 

 Orifices of the excrementitious organs anterior and lateral. 



This curious snail crawls slowly, feeling its way with the 

 inferior tentacula. The superior cannot be used for this pur- 

 pose; but they are in constant motion during the animal's 

 progress, and appear to be of essential service : they are often 

 shortened, so as to appear like mere tubercles ; but there are 

 no sheaths for their recession and protection. If the finger is 

 placed in the plate, about an inch before the creature, when 

 active and creeping, it will stop, turn back, and agitate the 

 tentacula, and then pass on to a side. The fasces are dis- 

 charged in pellets, like those of mice ; and, when the animal 

 is dying, a small quantity of an orange fluid sometimes escapes 

 from one of the lateral apertures. It is not common in Ber- 

 wick Bay ; but, in spring, a few specimens may generally be 

 found lurking under stones between tide-marks. They seem to 

 have left the deeper water to shed their spawn ; which is laid 

 on the under side of stones, in white gelatinous masses ; each 

 mass being formed of a chain-like, or beaded, thread, con- 

 voluted in every direction, and firmly attached by a colourless 



* In shape, they may be compared to the shell of a Sigaretus. 

 Vol. VIII. —No. 51. dd 



