British species of the genus Lagena. 15 



Manorbeer near Tenby, very rare, Mr. Jeffreys. Scarborough, 

 one specimen, Mr. Bean. Boston. 



Lagena striata, yav. perlucida. PI. I. fig. 11. 



Cell usually globular, sometimes broadest at the base, at others 

 ovate. Marked with longitudinal costse, which are very distinct 

 at the lower portion, but gradually lose themselves as they ap- 

 proach the long, elegant, tapering neck. In this it differs from 

 the last var., in which the strige terminate abruptly at the upper 

 part. Cell exceedingly thin and fragile, beautifully hyaline and 

 pellucid, sometimes of a pale milky tint, but more commonly 

 transparent as the purest glass. 



I believe this to be the Vermiculum perlucidum of Montagu : his 

 figure represents a highly depressed form of cell, furnished with 

 a small umbo at the base ; but as Montagu had never seen the 

 specimen, but only copied a drawing sent to him by Mr. Boys, I 

 suspect that some error exists. I have often seen the projecting 

 base of the central costa give the appearance of an umbo, and as 

 regards form I have observed very great differences. The number 

 of the ribs varies considerably. Some specimens, like Montagues 

 V. perlucidum, have not more than seven or eight, whilst in others 

 they increase in number so as to merge this variety in the ordi- 

 nary forms of L. striata, of which species I believe it to be one of 

 the young states. Its most common aspect is precisely that of 

 the ordinary fluted water-bottle used at the dinner-table. Some- 

 times the striae are so short and indistinct as to render the spe- 

 cimen almost undistinguishable from L. lavis ; indeed in some 

 few specimens the striae are only represented by a small circle of 

 minute tubercles forming a coronal at the base of the cell. 



Long. Diam. 



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Swansea, Tenby, Manorbeer, Sandwich, Kyleakin, Mr. Jeffreys. 

 " Seasalter, Mr. Boys." Montagu. Boston; March. 



L. substriata, nob. PI. II. fig. 12. 



Cell oval, sometimes considerably elongated and cylindrical, 

 |furnished with a long tubular neck. Surface marked with nu- 

 Imerous exquisitely delicate parallel longitudinal strise. 



At first I thought that this rare object was an extreme variety 

 of Lagenula striata, but after examining at least twenty specimens 

 I am nearly satisfied that it is a distinct species, as the lines vary 

 80 little either in their number, strength, or distance apart. The 

 general form of the cell also is much more ovate and elongated. 



i 



