BRACHIOPODA. 
147 
division by some authors. King* proposed to limit the term Crania to such 
species as are attached by the umbonal portion of the lower valve, e.g., C. Igna- 
bergensis, and to apply the name Criopus, which had been proposed by Poli in 
1791 ( loc . cit .) for the animal of Crania and some other brachiopods, to species 
attached by the entire surface of this valve. It is a well known fact that many 
species of Crania were quite unattached during their mature life, and other 
species are known to have been either attached or free. It therefore appears 
injudicious to ascribe a high value to so variable a character as the degree of 
attachment of the lower valve. 
Among Cranias generally there is a more or less distinctly developed tend¬ 
ency to the formation of a transverse posterior or cardinal margin, a feature 
reaching an extreme in Waagen’s genus, Cardinocrania. 
It is not usual to find among palaeozoic species any indication of more than 
two pairs of muscular impressions, the posterior being divaricators and the 
anterior, occlusors or adductors. The other small muscular bands rarely leave 
discernible scars, but their position may be learned from the accompanying 
figures of Crania anomala, Muller, reproduced from Dr. Davidson’s Monograph 
of Recent Brachiopoda,f and made from sketches by Mr. Albany Hancock. 
In addition to the large muscular bands are three pairs of smaller ones; da, 
va, the dorsal and ventral adjustors respectively, and bm the brachial muscles, 
* Monograph of the Permian Fossils of England, p. S4. 1849. 
f Trans. Linnean Soc. London, vol. iv, pt. 3, p. 187. 1888. 
