BY R. ETHERIDGE, JUNE., AND JOHN MITCHELL. 497 



faint; side lobes tumid, seven or eight pleurse on each; pleural 

 grooves very distinct anteriorly; sutures and axial grooves distinct. 



Ohs. — This species was described by Foerste from a specimen 

 sent to him by one of us. That specimen was distorted so that 

 the true features of the head were indiscernible, particularly those 

 of the eyes. In fixing the maximum number of lenses in the 

 vertical rows at nine he is in error, for in a number of eyes 

 examined by us the lenses in a row do not exceed five. By fore 

 and aft compression it is not unusual to find an eye with two rows 

 brought into the same vertical line, and in this way appearing to 

 have nine or ten lenses in a vertical row. This is probably the 

 case with Foerste's t3'pe specimen. 



We are inclined to agree with Foerste in ranking this as a species, 

 for certainly it is very clearly separated from P. fecundus, Barr., 

 by the greater inflation of the front of the glabella, the much 

 smaller eye, the less distinct groove passing under the front of the 

 glabella, the absence of granulation on the thorax, thinner test, 

 straighter sides of glabella, greater perpendicularity of the sides 

 of the thorax, greater distinctness of the pleural grooves on the 

 pygidium, smaller size of the animal, and above all the presence 

 of the very conspicuous dorsal spines. This latter feature 

 separates it from all species of the genus knoAvn to us. 



From P. Crossleii, nobis, it is not separable except by the dorsal 

 spines, and it may be that this feature is a sexual one, and the 

 two forms represent the male and female of the one species. In 

 a comparison of a number of heads of the two forms those of 

 P. serratus, Foerste, seem to be more tumid in front and to have 

 the glabella more sharply contracted behind by the intercalary 

 groove. 



Log. and Horizon. — Near Railway Station, Bowning, N.S.W. 

 Upper Trilobite Bed, Bowning Series — ? Wenlock. Coll. — 

 Mitchell. 



Phacops Sweeti, sp.nov. 



(PI. XXXVIII., fig. 9; PI. XXXIX., figs. 1, 2; PI. xl., fig. 10.) 

 [Compare Phacops (Odontochile) fecundiis, McCoy {Vnon Barr.), 

 Prod. Pal. Yict. 1876, Dec. iii. p. 15, t. 22, f. 8-9, t. 23, f. 1-6.] 



