KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 19. N:0 6. 51 



sidered as ranging very near to each other. The author says expressly »il u'existe 

 pas d'apophyses d'insertion a la partie antérieure». Its area is also described as large 

 as tliat in Chulodes. Sagtnaplaxus occurs in the »Dcvonien inférieur de la Sarthe» 

 and can indeed be said to be a more developed descendant of Chelodes. It is by 

 far larger and longer than the latter. 



1. Chelodes Bergmani Davidson & King. 



Fl. II ligs 1—8. 



Chelodes Bergmani 1874. Dav. & K. Oa the Trimerellidre etc. Qu. Journ. Geol. Soc. vol. XXX, p. 167, pl. 



18, fig. 14—14 a— d. 



Plates of conical outline, anterior margin straight or slightly eraarginated or even 

 convex, lateral margins eontinuing nearly parallel a little below the middle, then sud- 

 denly converging to form the acute posterior apex. Surface somewhat weathered, 

 shows faint traces of punctuate ornamentation on the transverse lines of growth. These 

 are most conspicuous near the lateral margins and they are parallel with the anterior 

 margin of the plate. In a transverse section the plate has the shape of a crescent, 

 being evenly arched, without any sinuosity on the back. The inside of the plate is 

 divided in two parts, of which the posterior, occupying exactly half the total length, 

 consists of the slightly excavated apical area. The transverse, gently arched lines of 

 growth resemble narrow, low ridges or callosities, they are very numerous and dense 

 and the whole area is raised a little above the anterior part of the valve. This is 

 longitudinally divided in two portions by a well marked sinus, towards which the sides 

 gently slope. This anterior surface is smooth, showing only indistinct traces of mus- 

 cular impressions towards the lateral margins, being near the sinus coarsely and lon- 

 gitudinally wrinkled. All around the lateral margins of the interiör surface there runs 

 an elevated narrow börder, formed, as it were, by the bending över of the exteriör 

 shell stratum. The plate is at its thickest in the median part and thins off towards 

 the apex. 



Height 20 millim., breadtli 13 millim.; thickness in the middle 5 millim., at the 

 apex 1,5 millim. 



Two specimens have been found in the uppermost limestone of Klinteberg and 

 a single plate in the oolite quarry near Gannvik in Grötlingbo. 



2. Chelodes Gotlandicus n. 



PI. II figs. 9—27. 



Plates cordate, with anterior margin deeply emarginated, posterior apex acumi- 

 nated, lateral lines, combining anterior margin and apex, gently curved. The plates 

 are generally longer than broad, much varying, as may be seen by the dimensions given 

 below, some even being transverse. They have consequently been placed in different 

 positions of the series. They are much more elevated along the median line of the 

 back, than in the former species and the sides are more sloping. In a transverse sec- 



