DR. T. DAVIDSON ON EECENT BRACHIOPODA. 63 



P. Fischer off the south-west of France, iu from 5 to 650 fathoms. It was also dredged 

 by Prof. Sars, Friele, and others off the Norwegian coast ; east coast of Shetland 

 (Fleming and Jeffrey.s) ; North Hebrides by Dr. W. K. Carpenter and Sir WyvUle 

 Thomson, in 170-050 fathoms, &c. 



Waldheimia cranium occurs fossil under the name of Terehratula euthyra, Philijjpi, 

 in the Upper Pliocene rocks of Valle Lamato in Calabria, and near Catancaro near 

 Reggio, at Gravitelli, Rometto, and other places near Messina in Sicily (Seguenza). 

 Prof. Sars and others quote it from the glacial and post-glacial deposits of Norway. 

 Waldheimia cranium has been recorded as from Ualifax in Nova Scotia by the late 

 Mr. Willis ; but I have been informed by Mr. Dall, Mr. Whiteaves, and others, 

 that w'hat he took for the shell under description w^as a specimen of Terebratella 

 ■spitzbert/emis. 



Obs. This species, its shell, animal, and different stages of development have been 

 carefully investigated and admirably described by several competent zoologists. It 

 has, however, been classed iu the genera Terebratula, Waldheimia, and Macan- 

 drevia. In 1859, Prof. W. King considered that the species should be separated from 

 Waldheimia, on account of the deviating septa and want of a mesial septum in the 

 dorsal valve, as well as bv the absence of dental lamina in the ventral one. I, how^ever, 

 with Mr. Dall, question Avhether the differences brought forward are of sufficient value 

 to warrant us in admitting it as a separate genus ; they are, at most, we think, sub- 

 generic differences. 



To Herman Friele we are indebted for a most valuable and important investigation 

 into the modifications assumed by its loop, from the very youngest age up to the adult 

 condition, which I now propose, in part, to transcribe from his memoir published in 

 1877. I also reproduce some of his figures on Plate XII., regretting that space will not 

 permit me to give them all. He says : — " The earliest stage at which a coherent apophy- 

 sary system of the Waldheimia cranium is observed, has a size of a little less than three 

 millimetres [1 line], the haemal valve being two millimetres [Plate XII. fig. 16]. Two 

 long thin lamellae project from tbe crura, connect with a filiform septum and run 

 together in an acute angle iu front, where they unite. By the connection of the lamelke 

 two close-set walls are given off, which by a refieetion form a tube, the posterior end of 

 which is closed. The size of the haemal valve has reached 2-5 millim., but the state of 

 things remains the same, save that both the loop (or the tube) and the lamellce have 

 expanded. [See PI. XII. figs. 17, 17 «] a the lamellae, b the two issuing vertical walls, 

 or the lateral walls of the tube, c the closed tube (or the loop). 



" The first visible change occurs hi/ an opening in the closed end of the tube [figs. 18, 

 18 a]. The united lamellas then begin to split apart at the anterior end. The haemal 

 valve has now attained the size of 4-5 millim. A continuous expansion of the loop- 

 complex causes a perforation in the lateral walls [PL XII. fig. 19], and the septum becomes 

 thinner and thinner. The next sizes observed were 5*2 millim. and 5-6 millim. (haemal 

 valve) [PI. XII. fig. 21]. The same characteristics as those seen in [PL XII. fig. 19] 

 are still in the main prevailing, but the connection with the septum is broken off, and 

 there remains but a little lump of the latter at the bottom of the valve. The wedge- 



