NO. 5 CAMBRIAN TRILOBITES 313 



CORYNEXOCHUS BORNHOLMIENSIS Gronwall 



Plate 55, figs. 2, 2a-b 



CorynexocJius hornholmiensis Gr5nwall, 1902, Danmarks Geol. Unders., 

 Vol. 2, No. 13, Bornholms Paradoxideslag, p. 137, pi. 4, figs, la, ib, 

 2; p. 217. (Described and figured as a new species.) 



Original description (in substance) . — " Only the central part of the 

 head and the tail are known. Head anteriorly without a sharp mar- 

 gin, curved, with a considerably expanded front. Dorsal grooves 

 diverge from the back toward the front, and end in a small pit ; they 

 are somewhat depressed posteriorly so that the front is club-formed 

 or somewhat pear-shaped. The front is anteriorly broadly rounded, 

 and in this place twice as broad as at the occipital ring. There are 

 either no lateral grooves, or two to three pairs, very weak and short. 

 The branches of the facial suture cut off a small part of the anterior 

 border outside of the front, and diverge strongly, going in an almost 

 straight line to the posterior margin of the head, whereby the fixed 

 cheeks attain an almost triangular periphery. The eyes are crescentic 

 in shape, medium large, occupying the foremost half of the distance 

 from the front to the posterior margin of the head. The cheeks are 

 pretty strongly curved, but not so smooth as the front. The occipital 

 groove is distinct, broadest along the outside. The occipital ring 

 narrow, with a little, short spine. 



" The pygidial shield is almost flat, about semicircular in form, and 

 retains its border. The median lobe is distinctly delineated, narrow, 

 and almost the length of the entire pygidium ; it has 4 or 5 segments, 

 which in the flat lateral lobes appear as indistinct ribs alternating 

 with the rings on the median lobe. 



" The cranidium is flat, with fine, depressed points. 



" Dimensions : 



Length of head 5 mm. 



Width of head 6 



Width of glabella anteriorly 3-5 



Width of occipital ring 1.5 



" Two specimens of the head and two of the tail are in the 

 Mineralogical Museum, associated with Paradoxides tessini and 

 Agnosttis parvifrons from Borregaard, 01e Aa. In the Museum of 

 Stockholm there are 13 specimens of the head and six of the tail, 

 which the writer examined through the courtesy of Professor Lind- 

 strom. All are preserved in limestone, labeled Bornholm, which 

 contains only very little of other petrifactions. One specimen is 

 associated with Agnostns nathorsti, Hyolithes socialis, Acrotreta 



