822 Lower-Carboniferous Entomostraca. By T. K. Jones. 



Leper ditia OTceni (Miinster), and their history is given, in the 

 "Ann. Mag. Nat. Hist." ser. 3, vol. xviii, 1866, pp. 39-40. 

 Some of their allies are described and figured op. cit., vol. xv., 

 1865, pp. 406, 407, pi. 22; but they have not themselves been 

 well drawn hitherto. L. suhrecta in length 2 millims., L. Scofo- 

 burdigalensis 1-5 millim. Their exteriors rarely bear the chief 

 Leperditian characters — excepting general form (and that modi- 

 fied) ; but intermediate gradations, among the countless 

 individuals that swarmed in the muddy lagoons nearly every- 

 where in the Carboniferous period, supply the deficiencies. Fig. 

 9 (an interior) shews a rather more exactly Leperditioid shape 

 than the other two, and bears a central (thickened ?) muscle-spot. 

 Pig. 7 and 8 are from the specimen of Lower M.-L. marked " C " 

 (Tweedmouth, see above, page 314); fig. 9 is a Tuedian speci- 

 men from " W," Edington Mill (see p. 316). Several others 

 of the hand-specimens, both Tuedian and Bernician, contain L. 

 Scotoburdigalensis, as shewn by the Table, p. 324, This variety 

 was wrongly referred by me to " Cytheropsis " in the " Monogr. 

 Foss. Estherise," Pal. Soc, 1862, p. 31, &c. 



7. Beyrichia crinita, J & K., MS. 



PI. II., figs. 10 and 11. 



This is a rather feebly developed BeyricUa, liable apparently to 

 much variation in its outline and transverse sulci, though the 

 pressure to which the probably thin valves have been subjected 

 may have caused some of the seeming j differences between 

 individuals. 



The valves are 1 millim. in length, oblong with rounded ends. 

 In fig. 11 the height is nearly frds that of the length ; in fig. 10 

 the height is proportionally less though the valve is larger. The 

 sulci give rise to three transverse ridges, of varying length and 

 variously disposed, sometimes at nearly equal distances, some- 

 times crowded towards one end of the valve — but doubtlessly 

 unequal pressure in the muddy deposit has modified the 

 ridges and the outlines of individuals. Occasionally two of the 

 ridges unite towards the ventral margin, as is usual with many 

 BeyricMce. The most interesting feature of this species, however, 

 is the fringe of fine spines, or hair-like prickles, set along the 

 front, lower, and hind margins of the valves ; about thirty seem 

 to have ornamented fig. 10 ; and much variation is seen in this 

 respect and otherwise, among the multitude of individuals 

 impressed on the black shale from Alnwick Moor, "B," low 



