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



canaliculi, which originate from the centre of the valve. In the middle there is a narrow 

 lanceolate area circumscribed by a corona of small lines, and marked transversely in the 

 centre by a few irregular lines. The border is delicately striated as well as the margins of 

 the canaliculi, and the centre of the interspace between two adjoining canaliculi is pro- 

 vided with a row of granules or denticules. 



In this form, as in most of the Surirellce, increase takes place at the two poles of the 

 longitudinal axis. 



The specific name has reference to the richness of the ornamentation which is found on 

 the valves. 



Surirella japonica, n. sp. (Plate X. fig. 8.) 



Elliptica ; canaliculis radiantibus, brevibus ; area centrali lanceolata lineolis terminata, 

 et nonnullislineis curvatis irregularibus quaudoque interrupts transverse signata ; margine 

 et areolis interstitialibus striatis. Ad mare Japonicum. 



This species, which was collected in the Sea of Japan, is very similar to the preceding. 

 It is elliptical in form, but its canaliculi are somewhat shorter than those in Surirella 

 dives. The extremities of the interstitial area are almost pedunculate, and are notably 

 removed from the hoop of small lines which limits the central lanceolate areola. More- 

 over, the entire area between the canaliculi as well as the margin are delicately striated. 

 The central area is much less elongated than that of Surirella dives, and it bears inter- 

 rupted and somewhat curved transverse lines, which do not exist in that frustule. 



Surirella argus, n. sp. (Plate X. fig. 9.) 



Valvis ellipticis ; area centrali hyalina arete lanceolata, irregulari et interrupto 

 lineolarum ordine finita ; canaliculis constrictis, areolis interstitialibus granulo vel ocello 

 signatis ; margine striate In mari Japonico. 



This frustule, which is also from the Sea of Japan, is provided with perfectly elliptical 

 valves. Its centre presents a narrow area, which does not exhibit any distinct markings, 

 and which is circumscribed by an irregular or interrupted series of small lines. Its 

 canaliculi exhibit a notable contraction in the middle, and the small interstitial areolae 

 that result are each marked by a granule or ocellus. The margin is delicately striated. 



Surirella ocellata, n. sp. (Plate X. fig. 7.) 



Panduriformis ; superficie centrali tereti, a qua canaliculi procedunt ; margine et alis 

 marginalibus striatis, spatiis interstitialibus ocello distinctis. Ad mare Japonicum. 



This Diatom, which, like the preceding, was procured in the Sea of Japan, is panduri- 

 form in outline, and though somewhat large it is singularly elegant. It is not provided 

 with a central area circumscribed by small lines ; on the contrary, the centre is smooth, 

 and from it spring .the canaliculi that adorn the perimeter. The border of the valve as 



