116 G. F. MATTHEW: ILLUSTRATIONS OF 



the glabella are placed on slightly elevated, transverse ridges. In this species the tuber- 

 cles are more equally distributed over the surface of the cheeks than in Ct. Malthewi- 



The test of this species is more heavily studded with minute elevations than the typ- 

 ical forms of other species of Acadian Conocorphea. The oiiter surface is covered almost 

 everywhere with little projecting tubercles, which are nearly equal in size, and appear to 

 be based on an outer film of the shell. "When this film is removed the test has quite a 

 different appearance, for, in place of closely set projections of nearly equal size and height, 

 prominences of two orders come into view, larger ones, of the natvire of hollow sjiines, 

 and smaller ones, similar in size to those on the outer film of the test, but more pointed. 

 The moulds corresponding both to the spines and the tubercles may be seen on the cast 

 of the inner surface of the test ; and it woiild seem that the hollow core of the spines 

 passes through the test, but that the apex of the core is veiled on the outside by tubercles 

 similar in appearance to the other tubercles with which the outer surface of the test is so 

 abtindantly studded. 



PYGIDIUM. {Fig. 30.) 



Broadly lenticular, and about half as long as it is wide. 



Axis sub-triangular, running the whole length of the pygidium. Marked by three 

 rings, beside the articulating facet, and a terminal lobe, which has a slight i^rotuberauce 

 on each side of the axial line, near the middle, and thence slopes abruptly and narrows 

 rapidly to the extremity. 



The side lobes of the pygidium have three ribs beside the half rib at the anterior mar- 

 gin ; the first two ribs are well defined, the third only by a furrow in front ; all arch back- 

 ward and downward to the margin. The two first ribs are crossed by narrow, faint fur- 

 rows, or striœ, from the anterior side of the inner end to the posterior side at the outer end. 



Sculplure. — The outer surface is distinctly granulated all over ; on the intermediate, or 

 under surface, sometimes a single, sometimes a double row of small spines can be detected 

 on the two first rings of the axis and ribs of the lateral third (about four spines on the 

 rings and about six on the ribs.) The mould of the inner surface is smooth. 



This pygidium is svrpposed to belong to C. elegans, because it is one of the three most 

 abundant pygidia of Conocoryphean type found in the shales of Division 1 c. at St. John ; 

 the granulate and punctate surface also accords with the ornamentation on the test of 

 this species. 



Varieties. (Fig. 34.) 



Var. a. granulatus. This differs from the typical form in the absence of spines and 

 tubercles, the surface being closely granulated ; only large individuals are known ; the 

 most perfect had very wide cheeks and three raised bars across the summit of the glabella ; 

 the front of the marginal fold appears to be narrow and not triangular, but this may be 

 an accident of preservation. 



Growth and Development of the Young. 



The series of heads of this species is defective and the history of its growth is there- 

 fore imperfect. 



