48 THE VOYAGE OF H.M.S. CHALLENGER. 



Expedition on March 25, 1878, west of St Thomas, Danish West Indies, at a depth 

 of 390 fathoms. 



Observations. — None of the examples exceeded the proportions above given, and they 

 look as if they were young and immature specimens of some species at present unknown. 

 I have in my collection a number of young specimens of a Magasella, agreeing in size and 

 shape with the one under description, which were dredged by Commodore Acton in the 

 Straits of Magellan. I felt inclined to consider these last as the young age of Tere- 

 hmtella dorsata, which occurs in vast abundance in the same Straits. It will hereafter 

 have to be ascertained whether Magasella is really a good sub-genus, or if only a modifi- 

 cation of Terebratella due to age. Terebratella may have undergone modifications in the 

 development of its loop, as is now well known to have been the case with Waldheimia. 



Magasella cumingi, Dav., sp. 



Terebratella cumingi, Dav., Proc. ZooL Soc, p. 78, pi. xiv. figs. 10-16, May 1852. 

 Magasella cumingi, Gray, Catalogue of the Brachiopoda of tlie British Museum, p. 99, 1853. 

 Terehratula cumingi, L. Reeve, Conch. Icon., Terehratula, pi. viii. fig. 29. 

 Magasella cumingi, Dall, Proo. PhD.. Acad. Nat. Sciences, p. 188, July 1873. 



Shell ovate, longitudinally oval, very thick, flexuous at the margin. Larger or ventral 

 valve most convex, slightly keeled. Beak large, acuminately produced, very slightly 

 incurved and truncated by a small oval-shaped foramen. Area triangular, concave, 

 laterally sharply defined. Dorsal valve slightly and uniformly convex. Surface of valves 

 smooth, whitish, or feebly tinted with red. In the interior of the dorsal valve the 

 cardinal process is large and massive, a mesial elevated triangular septum arises from 

 under the cardinal process, and by a gentle curve reaches and touches the bottom of the 

 larger valve near to its anterior portion, and from which it descends by an almost 

 perpendicular line to the bottom of the valve. The calcareous riband-shaped lamellse 

 forming the loop proceed from the base of the inner socket walls, directing themselves by 

 a gentle curve to the anterior portion of the septum, to which they adhere prior to being- 

 reflected so as to form a loop. The brachial or labial processes are of a brilliant red 

 colour. Length 11, width 8 mm. 



Observations. — In 1852, two examples of this small and interesting species, so remark- 

 able on account of the great thickness of its valves, large projecting beak, and interior 

 peculiarities, were sent to Mr Cuming as having been dredged ofi" New Zealand, and were 

 put into my hands by him for description and illustration. I placed it into the genus 

 Terebratella, on account of the shape of its loop, which is doubly attached ; subsequently 

 Mr Dall located it into his genus or sub-genus Magasella, on account of the shape of its 

 large triangular septum. 



Habitat. — The exact habitat of the species was not then positively known ; and I 

 have no certainty that it was ever dredged off New Zealand. In 1877 I ascertained 



