The Opisthobraiicliiata of South Africa. 109 



Sigarctus plamdatus, Eecluz. Sowerby, Thesaurus, v., 1887, p. 42. 

 No. 14, tab. 442, figs. 29-30. 



PI. X., figs. 4-16. 



Two specimens were dredged off Umvote Kiver from a depth of 

 27 fms. from sandy bottom with shells. They were of quite the 

 same size, now very hardened and very difficult to examine ; in the 

 male individual the shell was well preserved, in the female broken 

 in pieces. 



The colour was dirty yellowish gray. The length 4 cm., of which 

 the propodium measured 1-7 ; the breadth of the propodium behind 

 13 mm., at the anterior narrower. 



The milk-white fine shell on the middle of the animal 16 mm. long 

 by a breadth of 11 and a height of 5, with a very thin yellowish 

 cuticle. An operculum was not present. 



The propodium broader behind, sloping towards the rounded 

 anterior end, flat and even ; its straight hinder brim covering the 

 head and the margin of the gill cavity ; the propodium is separated 

 by a furrow from the sole ; behind this furrow passes in the flatter 

 furrow at the margin of the tail. The hinder foot, the tail is gradu- 

 ally pointed backwards and sloping, rather convex, even, along the 

 margin accompanied by a furrow ; its anterior end concave, thinner, 

 and with a height up to 13 mm., reflected on the shell, whose hinder 

 end partly covers its outer lip. 



The broad, short liead (fig. 4) with rather (4 mm.) long tentacles ; 

 the intestines shone blackish through the floor of the gill cavity. 

 The nearly cylindrical j/je?ws (fig. 7) 15 mm. long by a diameter of 

 1-1*5, with a hollow at the end, from the end of which the sperm- 

 duct projected ; along the side a superficial furrow. The clear 

 yellow gill (fig. 5) 13 mm. long with a breadth up to 3"25 ; its fine 

 leaves (fig. 6) free for about half their length. The olfactory organ 

 (Spengel) dirty brownish, nearly as long as the gill by a breadth of 

 1-25 mm., bent in its anterior end. 



The brownish gray bulbus pharyngeus of oval form, nearly 2 mm. 

 long. The mandibles nearly reaching each other above and below ; 

 brownish yellow, 0-75 mm. long by a breadth of 0-5 ; their elements 

 as in other Sigareti, 0*10 mm. long (fig. 8). The very faint yellowish 

 rasp of the tongue containing about 30-36 series of plates ; the long 

 sheath (fig. 16) of a breadth of 0-20 mm., bent several times, affixed 

 to the oesophagus and the salivary glands, contained a much larger 

 number ; the number of rows seemed in the two individuals to be all 

 in all 131 and 145 (^). The plates nearly colourless ; the breadth 

 of the median 0"13 mm., the height of the lateral plate 0*11, of the 



