150 Dr Grant on the structure of the Lerucea elongala, 



regularly cylindrical, and taper almost imperceptibly to near 

 their extremities, where they taper more suddenly, and ter- 

 minate in four small round fleshy tubercles surrounding a very 

 small amber-coloured horny disk. They are covered with a 

 thick, transparent, colourless, and tough membrane, deeply 

 marked transversely with numerous corrugations, and through 

 which we can perceive with a common lens numerous white 

 longitudinal striae composed of muscular filaments. The out- 

 er transparent membrane appears quite homogeneous. The 

 two horny disks of the tentacula were applied closely to each 

 other, buried in the substance of the cornea, and covered with 

 a hard transparent amber-coloured substance, which cemented 

 their concave surfaces firmly together. Other fourteen cir- 

 cular diseased marks were discoverable on the transparent cor- 

 nea, occasioned either by the bites of the same animal, or by 

 the attachment of different individuals. The interior of the 

 tentacula contained a white soft flocculent matter, surrounding 

 a thick central fasciculus of very coarse straight stiff fibres of 

 a grey colour, extending the whole length of the tentacula. 

 The white longitudinal muscular bands were very distinctly 

 seen on the inside of the tough covering of the tentacula, and 

 a tough white filament, sending off branches like a nerve, was 

 found running along the whole cavity of each tentaculum. 

 This nervous filament was proportionally as large and distinct 

 as that found in the central cavity of the arms of cephalopo- 

 dous animals. There is a very thin layer of white transverse 

 muscular filaments surrounding the tentacula exterior to the 

 longitudinal bands. On examining the extremities of the 

 tentacula under the microscope, I could perceive no reflected 

 teeth on the tubercles or disk for piercing, as we find on the 

 anterior tubercles of the Echinorynchus and other entozoa. 



The head is shaped like the body of a common spider-crab, 

 being broad and round behind, and tapering to a point on the 

 fore part. It is convex, smooth and glistening above, and on 

 each side of its anterior margin there is a small white knotted 

 process (c) like the rudiment of a jointed antenna. Immedi- 

 ately below the beak we observe the circular extremity of a short 

 cylindrical tubular proboscis, (h) at each side of which there 

 is another very small and soft antenna, (n, ii.) Beneath this 



