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



identification, at Station 195, October 13, 1874, lat. 0° 48' S., long. 126° 58' E. Depth, 

 825 fathoms. Two fragments also of a Terehratula at Station 13, March 4, 1873, 

 lat. 21° 38' N., long. 44° 39' W. Depth, 1900 fathoms. Bottom temperature, l°-9 C. 

 Globigerina ooze. 



TerebratuUna, D' Orbigny . 



Terebratulina ivyvilUi, Dav. (PL I. figs. 1, 2). 



Shell large, trigonal, longer than wide, broadest anteriorly, tapering posteriorly, light 

 yellowish. Dorsal valve triangular, anterior angles rounded. Hinge-line obtusely angular, 

 moderately convex, somewhat flattened along the middle, and abruptly bent inwards close to 

 the margin ; lateral sides of umbo auricular. Ventral valve convex, deeper than the opposite 

 one, flattened anteriorly, abruptly bent inwards close to the margin. Beak incurved, trun- 

 cated by a large oval-shaped foramen, separated from the hinge-line by a triangular con- 

 cave depression sharply marked laterally. Surface of shell nearly smooth to the naked 

 eye, but marked by very fine radiating raised lines. Shell perforations rather large. In 

 the interior of the dorsal valve the loop is short and simple, rendered annular by the union 

 of the oral processes. Length 63, width 50, depth 35 mm. 



Habitat. — A unique specimen of this fine species was dredged on 25th March 1873, 

 by the Challenger Expedition, ofi" Culebra Island, to the north-west of St Thomas, in 

 the West Indies, at Station 24. Depth, 390 fathoms. Sea bottom, mud. Mr Dall 

 informs me that he saw another specimen without name or derivation in the Museum at 

 Amsterdam. 



Observations. — TerebratuUna ivyvillii greatly exceeds in dimensions the largest known 

 .species of the sub-genus both recent and fossil.^ The animal was not preserved when sent 

 to me for description, indications of the mantle alone existing ; but WiUemoes-Suhm, 

 states in his MS. notes that it was " exceedingly small." From the character of the loop 

 the auricular expansions and striation the shell is naturally placed in the sub-genus 

 Terebratulina. The margins of both valves are abruptly bent inwards, as is so often the 

 case in adult specimens of several species of Tei^ebratula. I have much pleasure in naming 

 this remarkable new species after Sir Wyville Thomson, F.E.S., the distinguished director 

 of the scientific stafi" of the Challenger Expedition, one of the most successful undertaken 

 by any Government, and reflecting so much credit on all concerned. The scientific treasures 

 assembled during its course of 68,890 miles, comprise an incalculable number of scientific 

 results of the most interesting and valuable character. 



1 Waldheimia venosa, Solander, Vl?>^ = Ter. (jlohosa,'Let.'m. = Ter. fontainmna, D'Orb., is tlie largest recent BracM- 

 opod ■vvitli which we are at present acquainted. It measures when full grown, length 80, width 64, depth 45 mm. 

 The next largest recent Brachiopod is the Terebratulina wyvillii. The Terebratida grandis from the Upper Tertiaries 

 (crag) exceeded these proportions, some adult individuals having attained length 108, width 78, depth 55 mm. No 

 recent species of Terehxitvla with which we are at present acquainted have exceeded length 43, width 30 mm. 

 {Ter. vitmi). . 



