MARINE WOOD-BORING ANIMALS. 



397 



except for a small piece near tlie ventral angle. In anothei- 

 specimen (text-fig. 3, A, B), in which the lower part of tlie 

 auricle still remains, it extends onl}^ a very little below the level 

 of the anterior division of the valve ; on the inner surface it 

 is not defined anteriorly, passing with quite unbroken surface 

 into the postero-median division. 



The siphons (text-fig. 2, C), of wdiich the ventral, or inhalent, 

 slightly exceeds in diameter the dorsal, or exhalent, are separate 

 quite to the base. The fleshy collar which surrounds them is of 

 considerable size, and, in the contracted state of tlie preser\ed 

 specimens, conceals the siphons for about half of their length. 



Genus Xylotrya J. E. Gray. 



Xylotrya (Leach MS.) J. E. Grav, Proc. Zool. Soc. 1847, 

 p. 188." 



Whatever Leach's Xylotrya may have been (the reference by 

 Menke, Syn. Meth. Moll 2nd ed. 1830, p. 121 , and the description 

 by J. E. Gray, Syn. Brit. Mus. 44th ed. 1842, p. 76, suggest that 

 it was the genus now known as Xylcypliaga)^ the name appears to 

 have acquired validity only when Gray in 1847 referred to it the 

 Teredo hiiKihnulata of Lamai-ck. 



The species of tlie genus are for the most part sharply 

 differentiated from those of Teredo by the segmented blade of 

 the pallets. This blade is composed of a, series of hollow cones 

 successively ensheathing one another and arranged on a cential 

 axis forming a continuation of the stalk. The only approach to 

 a transition between the two genera that I have seen is found in 

 Nausitora diinlopei Wi-ight, in w'hich the ensheathing cones are 

 very numerous and closely set, and appear, in the solitary type- 

 specimen which I have examined, to be partly consolidated on 

 the inner surface. They thus come to resemble the laminae of 

 which the blade is built up in some, at least, of the species 

 of Teredo, differing from them, however, in their more regular 

 arrangement *. 



Many of the species referred to this genus have been only im- 

 perfectly described, and still more imperfectly figured. Possibly 

 the two species to which new names are applied below may be 

 identical with, forms already named, but they are certainly 

 distinct from any in the Museum collection. 



Xylotry^a austealis, sp. n. (Text-figs. 6, 7, k, 8.) 



Gcdohates saulii Hedley, Proc. Linn. Soc. X. S. Wales, xxiii. 

 1898, p. 94, figs. 7-9. 



Xausitoria saulii Hedley, Bep, Austr. Ass. Adv. Sci. viii. 190L^ 

 p. 248, pi. x. fig. 5. 



* Cf. Fischer, Journ. Concliyl. v. 1856, p. 131. 



