DR. T. DAVIDSON ON RECENT BRACHIOPODA. 57 



In the interior of the dorsal valve, tlu; eanlinal process is so small that it can hardly 

 be diirerentiated from the hinge-plate, and from under which a mesial septum extends 

 to one half the length of the valve. Loop long, simple and reflected, the lamella of the 

 reflected portion being wide, the principal stems nearly parallel. 



Rab. Off Norway, Finmark, &c., in 100 to 300 fathoms. Atlantic coast of Spain. 

 Dredged by the ' Porcupine ' Expedition at various northern stations, at depths from 75 

 to 755 fathoms (Jeffreys). In British Seas between Shetland and Faeroe, by Jeffreys 

 and J. Murray, in 345 to 570 fathoms. A'igo Bay (M'Andrew). Off Marocco and the 

 Canary Islands (' Talisman ' Expedition) in 331 to 861 fathoms. 



Obs. The shell and some parts of the animal have been carefully examined. Mr. Ball 

 says that its visceral area is very small, the muscular attachments being even smaller 

 than in Waldheimia floridana. The stomach, produced into a point without diffei'entia- 

 tion of the intestine, is very much shorter than in W. Jloridaiia. 



The development of the skeleton or loop in this species has been well studied and 

 illustrated in two papers by Herman Friele in 1875 and 1877, and by E. Deslongchamps 

 in 1S84<. Dr. Gwyn Jeffreys and myself have also followed out the same investigations. 

 Herr Friele begins by informing us that he has not been able to examine the first stages 

 in the development of the loop in this species, as he had done for that of Waldheimia 

 cranmm ; that the youngest examples of W. septigera he has seen measured 1, 2, and 3 lines 

 in length, and represented the second stage of JF. craii'mm, in which the united lamellte 

 begin to split apart at the anterior end ; and that the only essential difference at that 

 age is in the form of the septum, being 4'5 millimetres and 5*5 millimetres respectively. 

 The next stage he terms the Megerlla stage, the shell having attained 4 lines in length. 

 In this stage in Waldheimia cranium the lateral walls were broken down by an aper- 

 ture appearing in the middle of each and widening backwards. In W. septigera the 

 break occurs, on the contrary, on the posterior end of the walls, and extends in a forward 

 direction, the similarity at this stage to Terebratella being striking. The connection 

 between the process of the lamellae and the sejitum is severed in a specimen G lines in 

 length, and in a specimen 8 lines in length the lamellae are separated and the character 

 of the loop is that of the adult Wcddhehnia. In Plate XI., figs. 7, 8, 9, TO are from 

 Friele's memoir, showing the modifications above described. 



Waldlieimia septigera was described for the first time by Loven, in 1846 ; but having 

 neglected to give a figure of his species, the shell was very little known until 1855, when 

 I gave a figure of it in the Ann. & Mag. Nat. Hist. In 1863, in vol. ii. of his ' British 

 Conehology,' and subsequently in a paper in the Proc. Zool. Soc, Dr. Gwyn Jeffreys 

 erroneously maintained that Lov6n's Waldlieimia septigera was a synonym of Philippi's 

 Terebratnla sepAata, and this mistaken view he maintained to the last. In 1840, Signor 

 Seguenza, after much trouble and skill, examined the perfect loop in several adult 

 examples of Philippi's T. septata, and found it to be three times attached, as in Tere- 

 bratella, while the loop in W. septigera is only twice attached, as in Waldheimia. 

 The same indefatigable palaeontologist also examined the loop of his Pliocene Tere- 

 bratula peloritana, and found it to agree with that of Waldheimia septigera, of which 

 he admits it to be a synonym. 



SECOND SERIES. — ZOOLOGY, VOL. IV. 8 



