349 



trigonal ; ventral valve llattish, somewhat triangular, rounded; 

 mesial groove broad, indistinct ; internal appendage as in T. dor- 

 sata ; margin of the valves very slightly crenulated. 



Pound by Capt. King in the Straits of Magalhacns. Brit. Mus. 



13. Terebratula australis (pi. lxix. f. 25-33.) Quo//. T. 

 dentata and flavescens, Lam. 



Testa subovata, postice subacuminata, plerumque gibbosii, non- 

 nunquam subplanata, albicante, flavescente, vel subfusca, valvis 

 insequalibus, glabris, plerumque plus minusve (nonnunquam obso- 

 letissimc), radiatim sulcatis ; linea marginali rectiuscula, antice 

 plus minusve sinuata ; valva dorsali postice subacumiata ad apicem 

 obtusa, reflexa ; carina median! lata, inconspicua, foramine medio- 

 cri, integro, area cardinali lata, subinconspicua, marginibus rotun- 

 datis ; deltidiis magnis, coalescentibus ; valva ventrali subcirculari, 

 gibbosiusculaj sulco mediano inconspicuo, lato ; ossiculo interim 

 magno, f testae longitudinis, amenta ut in T. dorsatd efformante, 

 amento supero maximo; margine valvarum plerumque dentato, 

 dentibus plus minusve numerosis, magnis vel parvis, nonnunquam 

 rotundatis vel obsoletissimis, interdum maxiinis, prsecipuc illis eftbr- 

 mantibus lateres sulci mediani. 



Shell nearly oval, slightly acuminated posteriorly, generally 

 rather gibbous, sometimes slightly flattened, whitish, yellowish or 

 brownish ; valves unequal, smooth, generally more or less (some- 

 times very obsoletely), radiately grooved ; marginal line nearly 

 straight, more or less sinuated in front ; dorsal valve somewhat 

 acuminated posteriorly, obtuse, reflected, with a broad, indistinct 

 mesial ridge ; perforation of moderate size, entire, round ; cardinal 

 area broad, rather indistinct, with rounded edges ; deltidia large, 

 united in the middle ; ventral valve nearly circular, gibbous, with 

 a broad and indistinct mesial groove ; internal appendage as in 

 T. dorsata, the upper loop being very large; margin of the valves 

 generally toothed, teeth more or less numerous, large or small, 

 sometimes rounded, sometimes very obsolete, sometimes very large, 

 particularly those which form the sides of the mesial furrow. 



The varieties of this species are numerous, and they have been 

 described under several names, we have preferred using that 

 given by Quoy, as properly including all, and we have represented 

 the following, viz. — fig. 25, 28, two views of a variety with few 

 large radiated grooves and correspondingly few and large marginal 

 teeth ; fig. 26, 27, another variety with more numerous radiated 

 grooves and consequent smaller and more numerous marginal 

 teeth ; fig. 29, 31, two views of a variety with rather obsolete 



