TESTACELLA SCDTULUM. 



15 



Description. — Animal tawny-yellow, more or less freely speckled with brown, 

 especially on the back ; soi.l? and foot-fringe orange-yellow, most vivid near the 

 tail ; LATERAL GROOVES distinct and originating in a common depression in advance 

 of, but connected with, the peripallial furrow ; the mid-dorsal sculpture so distinct 

 in T. iiumgei is only very faintly indicated. When contracted it usually assumes a 

 semi-globose form somewhat dissimilar to the lenticular shape of lud'wtidea or the 

 short, cylindrical aspect of inaugci. 



Shell narrowly auriform, UPPER SIDE flat or even actually concave, lines of 

 GROWTH comparatively line, PEPaosTKACUil rusty-brown, and more persistent than 

 in maicgei or haliotidea, the colour showing internally through the thin outer margin 

 of shell ; NUCLEUS nearly central, placed at an angle of 60 to 70 deg. to the vertical 

 line of the shell ; COLUMELLA glossy-white, broad and angularly concave, terminat- 

 ing abruptly at the anterior margin of the shell. Length, 7 mill. ; the greatest 

 width, about 4 mill., being about the midille of the shell ; alt., IJ mill. 



Internally, the alimen'I'arv system displays a short ojsophagus, which 

 opens into a somewhat brownish crop, 12 or 14 mill, long, which shows longitudinal 

 whitish stripes, due to longitudinal plaits within ; the ])aired white salivary glands 

 are 5 or 6 mill, long, attached to its sides, and do not blend together ; tlie vestigial 

 stomach is of a pur])lish colour, about 3 mill, in diam., and is placed at first bend 

 of gut, just before receiving the stout and white bile ducts ; the gut, which is very 

 thick and firm, traverses the digestive gland, afterwards nan-owing into a slender 

 rectum, which opens as usual on the right side beneath the shell. 



The REPRODUCTIVE ORGANS simple ; OVOTESTIS fiesh-coloured with long acini 

 and imbedded within digestive gland ; DUCT whitish, convoluted throughout, and 

 entering the albumen gland about the middle, 

 from whence to outlet it is fused to gland ; 

 ALBUMEN GLAND large and broad, ochreous 

 or reddish amber ; ovispermatoduct wide 

 and compressed, the two channels well united ; 

 OVIDUCT in many broad, close-set plaits ; 

 sperm-duct broad throughout and of a buff 

 colour ; VAGiN.v very long, slender below, 

 much dilated above and abruptly doubly- 

 flexed ; sperm.vtiiec.v globular, reddish- 

 brown, with dull white mottlings when 

 mature, closely attached to the middle of 

 ovispermatoduct ; stem of spermatheca com- 

 paratively short and bent, slender above and 

 gradually enlarging to base ; VAS deferens 

 long ami simple, entering the penis sheath at 

 its apex close to the retractor ; penis sheath 

 long and opaque-white, narrow at base, but 

 increasing in diameter as it passes upwards, 

 the upper half broad and rigitlly doubly 

 flexed ; RETRACTOR ^■ery long and ribbon-like, passing fieely over the dorsal surface 

 of visceral mass and affixed near shell at caudal end of body ; ATRIUM very short. 



The RETRACTORS of the tentacles are shorter than those of T. haliniidcn or T. 

 maucfei, and more exactly symmetrically in their points of attachment to the integu- 

 ment close to the junction of the sole 

 with the sides of the body; they run 

 free, as usual, along each side of the 

 lingual sheath, dividing into the usual 

 two branches for upper and lower ten- 

 tacles before reaching brain ring ; the 

 bands are ribbon-like and of nearly 

 uniform widtli throughout, but spread- 

 ing at the roots for firmer hold. 



The LINGU.AL SHEATH is enormous, 

 forming a firm, tough, j^early bo<ly, 

 anteriorly nearly cylindrical, but taper- 

 ing off behind into a very powerful 

 muscle, composed of two, three, or ionr partially independent muscles, as in T. 

 mnugei, and having in addition its hinder half attaclied laterally to the skin of the left 

 side'by a series of five to ten pairs of conspicuous muscular bands running parallel 

 to eacii otlier and fixed at independent points. 



Fig. 21. — Sexual organs of T. scutulum X \\. 



(Chiswick, Mr. S. C. Cockerell). 



allKg. albumen gland ; oi. ovolestis ; p^<. 



oviduct ; p.s, penis sheath ; r.m. retractor 



muscle ; sp. spermatheca ; sp.d. sperm duct ; 



v.d. vas deferens. 



Fig. 22. — Lingual sheath of T. scutuJuw X l.V, 

 Hornsey, collected by Mr. H. Waliis K.ew, illustrat- 

 ing the retractor muscles of the tentacles and 

 lingual sheath. 



