KONQL. SV. VET. AKADEMIENS HANDLINGAR. BAND 34. \:o 8. t',, 



Platymetopus Angelin. 

 Pl. planifrons Angelin. 



Pl. IV figs. 50, 51. 



This genus may well be köpt distinguished from Lichas in con9equence of its pecu- 

 liar hypostoma and its still more peculiar maculae, not to remind of the other deviating 

 features. The maculae lie ;it the end of narrow, sigmoid grooves of fheir own above th<' 

 long transverse groove, separating the posterior börder from the anterior elevated raoiety. 

 They are elongated, eurved and entirety covered with a great number of irregular lenticles, 

 translucent through the thin covering membrane. 



Pliomera Ang. 

 Pliomera Törnquisti Holm in Trilobit. Dalecarliens p. 5 fig. 2. 



While Pl. Fischeri and Pl. actinura not have an}- hypostomic maculae, this species, 

 which Dr. Holm with some doubt joins in the same genus, has a hypostonia, which as to 

 its general shape resenibles that of both the mentioned species, evenly rounded at its 

 posterior horder, with a shallow groove encircling the central field. A little below the 

 horisontal diameter of this the maculae stretch obliquely inwards and downwards. They 

 rest on a little elevation and are elongate, anteriorly accuminated. The figure on Holm's 

 plate does not show the maculae. 



Proetus Steininger. 



There are some indistinct indications of macula3 in several of the hypostomas figured 

 in Barrande's Systéme pl. 1"). 



Proet. signatus Lindstr., Gotl. Trilob. Pl. XV fig. 17, shows verv distinctly the two 

 maculae. 



Proet. concinnus Dalm. 



Pl. VI figs. 19—23. 



In this, as well as in the few other species of Proetus which we have studied, 

 there is that peculiarity of the surface of the hypostoma that two more or less distinct 

 ridges form an acute angle just below the faintly arcuated anterior börder. The terrace 

 lines are exactly alike those of the Phillipsiaä, only visible on the central field and 

 ceasing just above the maculae, where there is a transverse smooth field. The posterior 

 margin has two pair of very short points, one on each side. The maculae are lengthened 

 tubercles, somewhat bent and have an oblique position. They are surrounded by tiny 

 priokles and as seen in fig. ~2?> the macula proper forms a white, elliptic spöt on tlie 



