390 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 



Ill t-lic Fiisiiliiiii limestones of Sicily Ihoi-o iw found u group of spiriferoids which 

 differs from the known genera. These fossils have an ornamentation which in some 

 M'ays i-ecalls that of Athyris. However, the complete absence of dental and septal 

 plates, and the form of the brachial apparatus, whi(;h I was able to oljserve in two 

 specimens, have convinced me that they differ from that genus; while, on the other 

 hand, they are more closely allied to the Martinise and the Retieularise. These 

 spiriferiods, to which I give the generic name Squwmularia, have the following 

 characters. 



Thejr are thick shells, imperforate, and ornamented with thin, concentric laminse, 

 narrowly nndulated, squamose, fringed, and imbricated one above the other. Here 

 and there, at nearly equal distances, some of these laminaj are thicker, more promi- 

 nent, welt-lilve, and with margins more distinctly fringed. The surface of the shell 

 shows numerous scars and imprints of spines, particularly distinct on the edge of the 

 varices. The hinge line, which is much shorter than the major breadth of the shell, 

 is slightl}^ arched. The area is often indistinct. Beneath the beak of the ventral 

 valve is seen the delthyrium, which is triangular and narrow. The epidermis is not 

 punctate. 



They liave no dental or septal laminee whatever. The crural plates start from 

 the hinge margin of the dorsal valve, more specially from the internal face of the 

 dental fossettes. These plates at first diverge, forming an elbow, and then converge 

 toward the median line, approaching each other so as to circumscribe in the internal 

 subapical region a space with pentagonal outline. Having come close together and 

 almost in contact, they give rise to the descending laminai, which extend parallel along 

 the median line as far as the anterior third of the length of the dorsal valve. Thence 

 they diverge toward the sides, to give rise to the formation of the laterall}^ directed 

 spiral cones. The latter are large enough almost to fill the internal cavitj' of the 

 shell, and are the result of brqad gyrations, few in number. 



The relationship of the Squamularise with the Martinim and the Heticularise is 

 close, but not so intimate that thej^ can be embraced within the same generic limits. 

 The 3£artinise have a punctate epidermis, and never present the ornamentation jjecul- 

 iar to these fossils. When they are provided with lamellose, concentric striaj, as, for 

 example, Martinia lamellosa Gemm., these striae are neither fringed nor wavy, and, 

 with the exception of Martinia distefanoi, lack spines. As regards their brachial 

 apparatus also there are differences. In the Martinise th,> crural plates convei-ge 

 abruptl}^ toward the median line, and leave between them in the rostral region a 

 larger or smaller triangular space. The descending laminae are close together for a 

 short distance, and then diverge toward the sides to give rise to the spiral cones, 

 which are rather small. 



As regards their affinitj^ with the Retieularise, there is some analogy in the con- 

 formation of the various parts of the apical region and in the sum total of their 



