( 480 ) 



of almost rod-like appearance, sometimes even narrower than that of sarpedon 

 teredon. The apex of the dorsal lobe is mostly rounded. The dorsal ridge is deuticn- 

 late in the fonr specimens in the Tring Mnseum, but a comparison of f. 123 with 

 f. 108 shows that the basal half of the ridge is very feebly raised; as in tciedon 

 (f. 117), the elevation is restricted to the median part of the ridge and the 

 transverse ridge. F. 121, 132, 123, 125 are taken from the same indi\ndual ; 

 122 and 123 give a view from the apical and ventral sides of the valve respec- 

 tively, while f. 125 represents tlie median part of ridge alone in a view from 

 above (as in f. 121). The dorsal ridge of anotlier individnal is rcjiresentcd from 

 the ajncal side in f. 124 ; the transverse ridge is here much less developed than in 

 the other specimen, in fact not more than in the Mindoro example represented by 

 f. 112; the ridge d of the latter is, however, scarcely indicated in f. 124; the 

 transverse ridge of f. 124 is enlarged in f. 120, which gives it in a view from 

 above. The differences between f. 122 and 124, and 125 and 120, are very con- 

 spicuous. 



f. P. sarpedon timorensls from Timor and AYetter; f. 128, 12!i. 



We have only two specimens of this interesting form, one from Dili, 

 Portuguese Timor, and the other from Wetter ; the two individuals disagree 

 somewhat with one another in external characters as well as in the form of the 

 transverse ridge, but tlie differences are such that they may very well be individual 

 and not subsin-cific. 



The valve agrees with tiiat oi jt/i/aitx, but the ventral lobe is less slender. The 

 dorsal ridge, as in teredon from Ceylon and South India, is not denticulate ; the 

 transverse ridge is tooth-like, nearly as in teredon ; f. 128 (Wetter) and 129 

 (Timor) rejiresent the transverse ridge in a view from above ; the figures may be 

 compared with f. 125 and 120 (Sumba), 132 (Queensland), 138 (New Britain), 143 

 (Celebes), and 148 (Guadalcanar, Solomon Islands). 



g. P. sarpedon choredou from Australia and New Guinea (including the islands 

 near its coast); f. 130 to 132, 135 to 137. 



The specimens from Waigen and the northern parts of New Guinea are '\\i' 

 external characters sometimes slightly different from ordinary individuals from 

 Australia, and lead over to the next subspecies, which inhabits the Bismarck 

 Archii)elago. 



The sinus of the valve is very deep (f. 135, Queensland). The ventral lobe is 

 very prominent, its upper edge straight, its ventral (denticulate) edge evenly rounded; 

 in breadth the ventral lobe is intermediate between timorensis and Juf/ans on the 

 one side, and sarpedon sarpedon on the other ; in some examples the lobe is a third 

 broader than in others. Tlie dorsal lobe is in all examples we have seen rounded at 

 the apex. The fold e of f. 135 is more curved than in sai-pcdon sarpedon, and 

 takes about the same course as in sarpedon teredon. 



The dorsal ridge divides liasally in a dorsal (;•) and a ventral (.s) jiortion wliich 

 correspond to the two slight folds marked /■ and .s in f. !)6. Now, in very many 

 specimens both from Australia and New Guinea, only the ventral branch of the 

 ridge participates in the formation of a high transverse ridge, as in f. 135 and in 

 f 130 ; the latter figure is taken from an individual from Redscar Bay, British 

 New Guinea, and is a highly enlarged view of the transverse ridge and the 

 adjoining parts of the dorsal ridge. In this case the dorsal ridge is rounded off. 



