156 



drical tubercles, lying one behiud the other (Fig. 8). These ribs are 

 parallel except on the jugal tract, where they converge a little. 

 On the lateral areas are found many rainute round tubercles, which 

 are spread regularlj. The valve is round, a ridge not being de- 

 veloped (Fig. 5). 



All the other middle valves are of the same structure as the second. 



The eight valve is very large, so that the length is about the 

 same as the breadth. It has a very large central part and a small 

 and nearly vertical posterior area, so that the indistinct raucro 

 lies far behind the middle. The sutural laminae are short and 

 thin. As usual the central and posterior areas are sculptured 

 like the central and lateral areas of the middle valves; the ribs 

 on the central area however couverge much more strongly 

 (Fig. 6, 7). 



The interior of all the valves is white and does not show any 

 tracé of insertionplates. 



The underside of the animal is shown in Fig. 2. The foot is 

 much reduced, so that the anus is not fouud at the hinder end 

 of the animal. The gill-rows reaeh the middle of the animal; on 

 the left I found 11 gill-lamellae. The type of the gill-row is 

 adanal, for the hinder lamellae are smaller than those of the middle 

 part; but because the anus is throwu proximally, this gill-row 

 does not agree with Plate's defiuitiou of the adanal type: »die 

 hinterste Kierae liegt mit dem After in derselben Querebene" 

 (49, Bd. 2, Pag. 395). After the hindmost lamellae there is an open 

 space, so that this form is adanal »mit Zwischenraum", while 

 other species as Lepidopleurus medinae Plate, asellus Spengl., 

 cajetanus Poli and 9'issoi Nierstr. are of the adanal type »ohne 

 Zwischenraum". 



As to the girdle, this form has this great peculiarity, that 

 spicula are present only is a very small number. 1 several times 

 tried to find the spicula by isolation, but only found two spicules, 

 of which one is shown in Fig. 9. It is a long, thin calcareous 

 needie. As to the underside the case is even less favourable ; here I 

 could not find any spicula. This forms an important difference 



