On the PaJcvozoic Bivalved Entomostraca. 337 



nortce ; b, the two aortic valves ; c, remnant of the auricle ; 

 d, cavity of the ventricle, showing various diverticula. The 

 great muscular walls are kept apart by a style. 



Fig. 3. The aperture («) of the air-bladder, with its neighbourino- re- 

 ticulations and radii. Considerably reduced. 



Fig. 4. A few of the reticulations on the inner surface of the anterior 

 region of the swim-bladder. Natui'al size. 



XXX. — Notes on the Palceozoic Bivalved Entomostraca. — 

 No. XX. On the Genus Beyrichia and some new Species^. 

 By Prof. T. Rupert Jones, F.R.S., and Dr. H. B. Holl, 

 F.G.S. 



[Plate XII. t] 



Contents. 



Introduction, p. 338. 



I. Beyrichia, M'Coy, p. 345. 



1. Beyrichia tuberculata (Kloden), p. 347. 



(1) B. tuberculata, var. gibbosa, Renter, p. 349. 



2. B. Klcedeni, i^rCoy, p. 349. 



I. Lobes free and plump. 



(1) B. Klcedeni, var. granulata, Jones, p. 350. 



(2) Var. nihda, Jones, p. 351. 



(3) Var. antiquata, Jones, p. 351. 



II. Lobes less free, attenuated. 



(4) B. Klcedeni, var. intermedia, Jones, and subvar. std)- 



spissa, nov., p. 352, 



III. Lobes free and subdivided. 



(5) B. Klcedeni, var. subtorosa, Jones, p. 353. 



(6) Var. torosa, Jones, p. 354. 



IV. Lobes coalescing below. 



(7) B. Klcedeni, var. tuberctdafa, Salter, p. 354, and sub- 



var. elansa, nov., p. 355. 



(8) Var. scotica, nov., p. 356. 



3. B. concinna, nov., p. 356. 



4. B. Maccoyinna, Jones, p. 357. 



5. B. Jonesii, Boll, p. 359. 



6. B. admixta, nov., p. 359. 



7. B. lacunata, nov., p. 359. 



II. Bollia, gen. nov., p. 360. 



1. Bollia bicollina, nov., p. 361. 



2. B. unifiexa, nov., p. 361. 



III. Klcedenia, gen. nov., p. 362. 



1. Klcedenia intermedia, J. & H., var. marginata, nov., p. 362. 



Explanation of the Plate, p. 363. 



* For No. XIX. see Ann. & Mag. Nat. Hist, for March 1885, p. 174 

 t This Plate has been drawn under a grant from the Royal Society for 

 the illustration of fossil Ostracoda. 



