KONGL. SV. VET. AKADEMIENS HANDLINGAK. BAND 34. v 8. ~> I 



Chirums spinulosus Nieczkowski. 



I'l. III 6g. 15. 



We have had the interiör surface of ;i hypostoma al our disposal from the lower 

 Siluria of Esthonia (Kuckers C 2 ) belonging to Dr. <i. Holm. The maculae are svell pre- 

 served, standing out black 011 the white surface, oblong, L,5 millim. in srreatesl length 

 (fig. 15). There are indications as of a great number of small lenses <>n these maculae. 

 Remarkable are the two elongated spöts, almost •"> mm. in length, abovc these maculaii 

 of vvhich already mention has been made under Ch. clavifrons. 



Chirurus sp. indet. 

 Pl. III fig. 16. 



The hypostoma of an undescribed species Ironi Öland. The maculae are lengthened, 

 ellipsoid and smooth tubercles lying in a groove. The finely granulated surface of the 

 hypostoma shows rare smooth spöts interspersed, being on the inside smooth pits, from 

 which again in rasts of the hypostoma larger tubercles are moulded. 01' the same 

 nature are those that are visible on the nucleus of Chir. speciosus and others. There 

 are still some undescribed Lower Silurian species, for instance one nearly related to Ch. 

 conformis with tubercular maculae. A large hypostoma from the Leptaena limestone of 

 Dalecarlia, 33 millim. in length. has a longitudinal macula, '2 millim. in length. as seen 

 on the inside of the fragment. 



On pl. VI tig. 10 a little hypostoma is delineated that shows some reseinblance 

 with that of the Chirurus, but probably belongs to some other, unknown genus. It is 

 Upper Silurian, found at Mulde in Fröjel, Gotland. It is of an elongated ovate shape, 

 with the anterior horder faintly arched, the anterior wings hroad, truncate. A narrow 

 elevated horder surrounds the latera 1 and posterior margins. The somewhat vaulted sur- 

 face is eovered by fine granulations, and the macula 1 situated on equal distance from the 

 anterior and posterior margins are ovate, smooth and directed obliquely inwards. There 

 are two rninute pointed processes on each side of the lateral borders and one on each 

 side of the pointed posterior margin. 



Ctenopyge Linsn. 



Ct. spectabilis Br. (I, pl. XII, tig. 12 a). 



A small lengthened, apparently smooth hypostoma with two globular tubercular 

 macula' near the posterior börder. Xo mention made of them in the description of 

 Brögger. Cambrian. I am not, however, quite sure whether this really belongs to a 

 Ctenopyge, as it rather more resembles the type of a Peltura as shown in Pelt. scara- 

 baeoides. As Ctenopyge is so nearly related to Sphaerophthalmes it could be expected to 

 see its hypostoma of the same type and the maculae entirely wanting. The eyes of this 

 genus have been described a bo ve a t page 29. 



