494 



PROFESSOR GREGORY ON 



38. Denticula fulva, n. sp. 



39. ... marina, n. sp. 



40. Diadesmis (?) Williamsoni = Himanti- 



dium Williamsoni, Sm. 



41. Meridion (?) marinum, n. sp. 



(or Gomphonema lineare ?). 



42. Pyxidicula (Dictyopyxis) cruciata, Ehr. 



43. Orthosira angulata, n. sp. 



30. Denticula (?) interrupta. PL X., fig. 30. Form of F.V. nearly rectangular, 

 the middle part very slightly convex, and the ends a little expanded. There is 

 an apparent interruption of the margin at the middle point on each side, and on 

 each side of this opening is a round punctum. Length about 0-0015"; breadth 

 about 0*0004". It occurs in chains of 2, and the two dots of each margin form a 

 square with those of the margin of the adjacent frustule. The S.V. is not yet 

 known, and the species is only provisionally referred to Denticula. 



This species occurs in Lamlash Bay, but is scarce. 



31. Denticula (?) capitata, n. sp. PL X., fig. 31. Form of F.V. generally rec- 

 tangular, but with the middle part considerably convex, and the apices expanded 

 and rounded. Length about 0-0018" ; breadth about 00005". Occurs, like the 

 last species, in chains of two. S.V. as yet unknown ; and it is only doubtfully 

 and provisionally referred to Denticula. 



This species occurs only in one of the Loch Fine dredgings, and it is as scarce 

 as the preceding. 



32. Denticula (?) ornata, n. sp. PL X., fig. 32. Form of F.V. rectangular, but 

 somewhat expanded in the middle, and also, after a slight contraction, at the 

 apices, which are finally truncate. The margin, at the expansions, is beautifully 

 moulded, having a moulding or notch on each side of the middle point. — Occurs in 

 chains of two. Length 0-0015" to 0-0017" ; breadth, in the middle, 00005". S.V. 

 not yet known, so that the species is only provisionally referred to Denticula. 



This very pretty species occurs both in Lamlash Bay and in Loch Fine, and 

 is much less scarce than the two preceding ones. Notwithstanding this, however, 

 I have not been able to find the S.V. 



33. Denticula (?) Icevis, n. sp. PL X., Figs. 33, 33*, and 33 c. Form of F.V. 

 linear, rectangular, with a small sharp prominence in the middle of each margin, 

 and the apices slightly, but sharply, expanded. Occurs in chains of two or three, 

 and also solitary. Length from 0-0016" to 0-0027"; breadth 0-0006". It is 

 striated on each side to one-third of the width, indicating that the S.V. is convex. 



Strisedelicate, but distinct under a high power, about 48 in 0-001". The general 

 aspect is smooth, and the striation is only seen on very careful adjustment. There 

 are two terminal nodules visible on the F.V. at each end, which are joined by 

 lines bounding the striae. The middle prominence of the margin of the F.V. 

 seems to indicate a central nodule on the S.V., which view has not yet been ob- 

 served. 



This species is by no means rare in Lamlash Bay, and it occurs also in Loch 

 Fine; but I have hitherto been unable to detect the S.V. I have referred it pro- 

 visionally to Denticula, but with many doubts. It is probable that if we had the 



