Appendix to Part I. 177 



3. Spieieeea teapezoidalis. G. Soiverby. 



Spin/era, Testa subtetragond, mediand parte -profunda, radiis non- 

 nullis, subinconspicuis ; radiis lateralibus utriusque lateris septem 

 ad octo distinctis : long. 15, lot. 2*, poll. 



There are two specimens of this, in a dark, rusty, gray limestone, 

 probably bituminous. 



Spieieeea teapezoidalis, var. ? G. Sowerby. 



Spirifera, Testa radiis lateralibus tripartitim divisis,lineis incrementi 

 antiquatis, cceteroquin omninb ad Spiriferam trapezoidalem 

 simillimd. 



At first I hesitated to unite this to Spirifera trapezoidalis, but 

 observing that at the commencement the radiating ribs were simple, 

 and knowing that these are subject to variations, I have thought it 

 best merely to distinguish this specimen as a variety. 



There are several other, probably distinct, species of Spiriferse, 

 but as these are only casts, it is obviously impossible to give the 

 external characters of the species. Since, however, they are very 

 remarkable, I have thought it advisable to give a name, together 

 with a short description of each. 



4. Spieieeea paectcostata. G. Soiverby. 



Length equal to about two-thirds of its breadth ; ribs few and 

 variable. 



5. Spieieeea Vespeetilio. G. Soiverby. 



Breadth more than double its length, radiating ribs rather large, 

 distinct, and not numerous ; posterior inner surface covered with 

 distinct punctulations in both valves. 



6. Spieieeea avictjla. G. Soiverby. 



The proportions of this species are very remarkable, inasmuch 

 as it appears to have been nearly three times as wide as it is long ; 

 the radiating ribs are not very numerous, and the internal posterior 

 surface of one valve alone (the large valve) has been punctulated. 

 In its proportions it resembles Phillips's Spirifera convoluta, but as 

 our Sp. avicula is only a cast of the inside, its proportions are not 

 so abnormal as those of Sp. convoluta. 1 



A specimen, which is very much pressed out of its natural shape, 

 but which still appears to differ somewhat in its proportions, shows 

 not only the cast of the inside, but also the impression of the out- 

 side ; its radiating ribs are very irregular, and numerous, but it 

 must be regarded as doubtful whether some of them be not principal 

 and others only interstitial : their irregularity renders it impossible 

 to decide. 



1 ' Geology of Yorkshire,' part ii. plate ix. f . 7. 



