55 213 



Marseniidae. 



R. Bergh, malacolog. Unters. Supplcmentheft III, 1—2. 1886 — 1887. m. 14 Tal'. 



Marseuia, Leach. 



Marsenia perspicua (L.). 

 PI. III, Figs. 13—14. 



Of this form i specimens, 3 female, and one male, were taken on Dcbr. 30" 1 1900 

 at the coast of Lem Ngob, of which only the largest one was more closely examined. 



The largest one of the much hardened specimens which were kept in spirit, had 

 a length of Il mm , by a breadth of 9-5 mm , and a height of 5 mm ; the length of the foot-sole 

 was 6 mm by a breadth of 3-5 mm ; the length of the tail was3 mm ; the breadth of the mantle- 

 brim was almost 2 - 5 mm . The length of the smallest (male) specimen was 4 mm . — The 

 colour of the mantle-brim was gray on the upper side with numerous white spots shining 

 through, and with scattered black spots and stripelets; the back (fig. 13) itself was dark 

 gray with numerous whitish dots and a few black spots. The lower side of the whole 

 body was whitish gray, posteriorly and at the left side the shell shone through with a 

 strong whitish colour, and the whole contour of the shell was upon the whole highly con- 

 spicuous. The upper side of the tentacles and the neck were black, as was also the upper 

 side of the foot. 



When the whole mantle was removed from the shell, the inside of the whole (also 

 outwardly dark gray) middle part was seen to be gray with close-standing black spots, 

 between which a few white ones were sprinkled. 



The (slightly yellowish-) white, rather firm shell had a length of 7 - 5 mm , by a 

 breadth of almost 6 mm , and a height of 4 , 5 mm . Its form was as usual, the stripes of 

 growth rather strong. 



The form of the larger, more closely examined (female) specimen was the typical 

 one. The back was completely smooth. 



The central nervous system was quite as usual. 



The buccal tube was l - 25 mm long, black at the fore edge. The bulbus pharyn- 

 geus had a length of 2 mm , by a breadth of l-75 mm , and a height of 1.5 mm ; its form was 

 quite as usual. The mandibles were as usual; their fore end was yellow as far as the 

 fold, otherwise they were colourless. — In the slightly yellowish (up to - 30 mm broad) 

 radula of the tongue, 12 series of tooth-plates were found, under the tectum radulae 

 5 series, and in the long, rolled up sheath 33 series, of which the four hindmost ones 

 were still undeveloped; thus the total number of series was 50. The median plates had 



