BRYOZOA. 583 



The less strong and different form of the support, the more 

 rigid branches, more regular arrangement of the zooecia aper- 

 tures, and sub-quadrangular form of the fenestrules on the re- 

 verse, distinguish This species from L. ranosculum Ulr. Hall's 

 description of the obverse differs somewhat from the above, but 

 there can be no doubt about the identity of the specimens here 

 described with the original exampi 



I have failed to find any reliable characters upon which to 

 distinguish Hall's L. lyra from this species. Fig. 2a (PI. LVIII) 

 represents a small example of what I regard a# the typical form 

 of L. subquadrans, while fig. 2 and 2b represent examples that 

 are intermediate between it and the L. lyra form. A specimen 

 before me (obtained since the plates were lithographed) seems 

 to agree in every particular with Hall's description of his lyra. 

 It also agrees with figure 2 in every respect excepting slight 

 modifications in the form of the support, such as incurving 

 abruptly outward and upward from the slender peduncle or 

 base, instead of being nearly direct. Such small modifications, 

 unless accompanied by more important differences, are scarcely 

 sufficient even for varietal separation, since nearly every speci- 

 men examined by me offers some slight peculiarity. The L. sub- 

 quadrans being the normal and more abundant form, it seems 

 desirable that its name, although following L. lyra in the 

 original paper, should take precedence. 



Position and locality: Chester group. Rather common at 

 Chester, 111., and Sloan's Valley, Ky. 



LYROPORA QUIXCUNCIALIS Hall. 



PL LVm, Fig. 3-3d, and PL LV. Fig. 7-7c. 

 Lyroporo. quincuncialis Hall 1857. Proc. Amer Ass. Ad. Sci., vol. 10, p. 180. 



In this species the support is very much as in L. ranosculum, 

 but differs in being less strong and rather narrow oval instead 

 of subcircular in cross section. The fenestrated expansion is 

 also less convex, and in every respect the zoarium is less ro- 

 bust. Branches, on the obverse, rounded, 0.25 to 0.5 mm. wide, 

 with a series of small tubercles along the middle, and two 

 ranges of cell apertures excepting below a bifurcation where 

 there are three: 24 or 25 in one cm. Apertures small, about 

 0.07 mm. in diameter and twenty-five in 5 mm. Fenestrules 



