248 CEYLON PEARL OYSTER REPORT. 



primary meshes across the scale. The antenna? adhered together and broke away 

 from their peduncles. 



Lepidonotus carinulatus, Grube (1869) Plate L, figs. 7 to 11. 

 (See Gkube, 'Ann. Semp.,' 1887, p. 26.) 



Localities : South-west Cheval Paar, one specimen, broken in half, and several 

 specimens mostly fragmentary; Chilaw Paar, Station LXIX., one specimen. 



The antennae and dorsal cirri show a very slight distal dilatation followed by a 

 nagelliform terminal process. The cirri and palps are smooth ; dorsal seta? more slender 

 than ventral, 20 to 30 in number, disposed in three concentric arcs, the seta? of the 

 dorsal arc being shorter than the rest. Ventral setse about 25, bidentate and fringed 

 (Plate!, fig. 11). 



Elytral papilla? carinulate and spheroidal on the surface, echinulate and stellate 

 near the fimbriated border ; in some elytra the echinulate papilla? extend over the 

 surface to the region of the scar. Elytra deciduous and body fragile ; twelve pairs of 

 elytra. Exserted pharynx with fringe of nine dorsal and nine ventral marginal 

 papilla?. Some elytra become narrower towards the inner side than at the outer side, 

 others are nearly equally wide throughout, with concave anterior border. Patches of 

 dark brown pigment are scattered over the surface. The fimbria? of the outer border 

 are densely placed, those at the posterior border are sparser. Some scales are much 

 less papillose than others ; in a highly tuberculate scale the carinulate papilla? occupy 

 the anterior and inner (mesial) portions ; the echinulate papilla? occur at the posterior 

 border, extending thence over the scar, this region being somewhat elevated ; the 

 echinulate papilla? near the outer border are smaller and less hirsute than those of 

 the posterior border, sometimes presenting a more or less stellate appearance (Plate I., 

 fig. 10). The prostomium (cephalic lobes) with eyes and antennary bases (cerato- 

 phores) is shown on Plate I., fig. 7. 



Observations on a larger specimen, in which some of the elytra were better 

 preserved in position, show that the dominant macroscopic character of the species 

 lies in the difference between the elytra of the anterior region and those of the 

 middle and posterior regions. The anterior scales (only those of the fourth and fifth 

 segments are present in the specimen) are much smaller than the rest, they are 

 placed subtransversely and their surface appears verrucose under low magnification. 

 The more posterior scales show a finely granulose surface, they are about twice the 

 size of the anterior scales (excluding the scales of the first pair, which are generally 

 small and round, and are absent from this specimen), and they are longitudinally 

 elongate, the anterior end narrower. All scales show a large opaque whitish patch 

 in the region of the scar, and all are fimbriated externally. The length of the 

 specimen is 17 millims. ; total width over the seta? 5 millims. Along the posterior 

 border of the elytra there are small saucer-shaped elevations which appear to be the 

 bases of deciduous fimbria?. 



