12 JOHNSTON, ON DIATOMACK.E. 



way and in balsam, it was very easy to perceive that the 

 front view (or edge) of Spatangidum was not straight, but 

 sinuous or zigzag ; and it occurred to me that the rays of 

 both could not coincide when the valves were together. I 

 was fortunate in finding three individuals in pairs such as I 

 had wished. The colour is darker, of course, than that of a 

 single disc ; instead of seven rays there appear fourteen, 

 alternating in depth of hue; and the reticulation extends 

 uninterruptedly over the whole extra-hyaline area, but is 

 fainter in the course of a ray as it overlies the inferior inter- 

 radial network. Diameter ^W- 



From " Elide/' 



In the dry preparation all the rays are brighter than the 

 interspaces, and the reticulation over and under the former 

 more distinct. 



AsTEROMPHALUS, Ehr. 



Asteromphalus centr aster, n. sp. — Orbicular, of a pale 

 buff beyond the hyaline area, which is very slightly ex- 

 centrical. Rays straight, turgid in the area, diminishing 

 gradually, and terminating in a flattened nodule situated just 

 within the marginal line ; nucleal ray longer and narrower 

 than the others, which are inserted on its extremity, and 

 very near it on the sides. The hyaline area has a scalloped 

 border, convex inwardly, each inter-radial space being bisected 

 by a delicate secondary ray terminating outwardly in a 

 nodule, and about three sevenths of the radius in length. 

 Margin very finely dotted, showing best in lines at right 

 angle with the secondary ray. The crescentic edge of the 

 hyaline area and the rays beyond it bordered with minute 

 granules. 



The number of rays of this charming species is eleven, 

 and they are equidistant. I regret to say that 1 have found 

 but a single disc. Diameter s\-g". (PI. I, fig. 10.) 



In Elide guano. 



Campylodiscus, Ehr. 



C. productus, n. sp. — Valve inconsiderably bent ; elon- 

 gated and constricted at the middle. Canaliculi about one 

 fourth the transvci'se diameter, each marked by a small 

 node midway as it expands outwardly ; margin broken by 

 depressions not corresponding with the canaliculi, and bear- 

 ing a double row of small dots. Within the canaliculi, at 

 either extremity, an elongated crescent of fine granules 

 fading towards the centre. Diameters -j^t" x t&?"- 



In Elide guano. 



