KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 34. \:o 8. 19 



Centropleura Angelin. 



This author has delineated tnosl distincl maculae in Centr. Steenstrupi pl. III fig. 1. Ii. 

 two, small elongate darkish spöts, near the posterior margin. I have n<>t seen any specimen 

 of this trilobite and have consequently not been able to follow up Angelin's observation. 



Chasmops M'Coy. 



Pl. III Ii-. H» 



Iii liis work on the Russian Phacopidae Friedr. Schmidt lins given the figures of 

 Chasmops Eichwaldi and Ch. Wesenbergensis showing, as it were, patches of bläck maculae. 

 But as there is no mention of them, and as they are quite unlike the maculae \\ 1 1 iol i are 

 described here, I am in doubt of their rea] nature. We have figured a macula from the 

 hypostoma of a Chasmops, probably Ch. macroura, from n drift block near Rostock. It 

 is elongate and narrow, more t han four times longer than broad. Its smooth surface is 

 a little scooped ont and no structure is observable. 



Chirurus Beyrich. 



We lind the hypostomic maculae annotated and delineated as occurring in the fol- 

 Iowing species. 



Ch. bimucronatus Salter pl. 5, lig. 5 as two narrow elongated pits, surface scems 

 intact. No mention of them in the letter-press. 



Ch. exsul Schmidt pl. VI hg. 9. Indications of the oblong, narrow maculae. 



Ch. macrophthalmus Schm. pl. \" II, figs. 1 c, 2. Faint indications of narrow pits. 



Ch. Quenstedti Barr. Tal). 4"2 tig. 3. Maculae near lower horder as two narrow slits. 



Ch. spinulosus Schm. pl. VII tig. 10. The lateral pits well visihle. 



Ch. tumidus Schm. pl. VIII, hg. 22. The pits are short, but present. 



The exteriör surface of the hypostoma is entirely covered with small wartlets, 

 eloscly set, of different size in the various species, and spread between them lie a great 

 number of elongate smooth spöts dispersed, on the interiör side of the hypostoma show- 

 ing an excavated surface (pl. III fig. 16). 



Chirurus (Cyrtometopus) clavifrons Dalm. 



Pl. III figs. 17—21. 



The shape of the hypostoma is shown in hg. 21 pl. III. It is regularly shield- 

 fbrnied with posterior margin rounded. A shnllow groove running paralie] with the 

 margins forms a large, faintly elevated börder. The anterior margin projects on both 

 sides in a short, backwards directed, broad and flat wing, hollowed out with a pit on the 



