BIBLIOGRAPHY OF PALASOZOIC CRUSTACEA 111 
ULRICH (E. O.) and BASSLER (Ray S.)—Continued 
The valves are usually short, semi-elliptical in outline, and sharply lobed. 
Group Beyrichia Buchiana: 
The anterior and median lobes are joined, but the anterior lobe is thinner and the 
ventral connection proportionally thicker than usual, the combination giving to the 
united lobes a striking similarity to the horseshoe ridge in the B. uagula section of 
Bollia. 
Group Beyrichia tuberculata: 
‘This section comprises a number of species, in which the anterior and posterior lobes 
are broken up by minor furrows—the posterior lobe into 2, the anterior lobe into from 
2 to 6 or 7 node-like parts. Beyrichia Buchiano-tuberculata Reuter, would represent 
about the simplest type, and B. pustulosa Hall and B. Noetlingi Reuter the most complex. 
Group Beyrichia Salteriana: 
The species of this group are not as large as those of the preceding groups and 
differ in the fullness of their lobes and proportionate narrowness of the furrows. 
Group Beyrichia clavata: 
The small group includes B. Jonesii Boll, and possibiy B. umbonata Reuter. 
Subgenus Steusloffia, new. 
Group: Beyrichia Linnarssoni: 
This group includes B. antiqua, B. acuta, B. simplex, B. Linnarssoni, B. signata, B. 
beyrichiodes and probably B. erratica Krause. 
Group Beyrichia interrupta: 
The illustrations given by the authors show possible derivation of the B. interrupta 
group from Eurychilina, and its relations to Beyrichia clavata group and to Steusloffia. 
The authors place under Kloedenia the following species: 
Kloedenia apiculata Jones, K. Barretti (Beyrichia Barretti Wel.), K. centicornis n. 
sp.. K. concinna (Beyrichia concinna J. & H.), K. fimbriata n. sp., K. granulata 
(Beyrichia granulata Hall), K. initialis (Beyrichta initialis Ulrich), K. intermedia (B. 
intermedia J. & H.), K. intermedia marginaia J. & H., K. jerseyensis (Beyrichia jer- 
seyensis Weller), K. Kummeli (Beyrichta Kummeli Weller), K. mantliensis (Beyrichia 
mantliensis Wel., K. manliensis deckerensis (Beyrichia deckerensis Weller), K. margin- 
alis n. sp., K. montaguensis (RBeyrichia momiaguensis Wel.), K. nearpassi (Beyrichia 
nearpasst Weller), K. oculina (Beyrichia oculina Hall), K. parasitica (Beyrichia par- 
asitica Hall), K. praenuntica n. sp., K. punctillosa n. sp., K. retifera n. sp., K. scotica 
(Beyrichia Kloedeni var. scotica J. & H.), K. simplex Jones, K. Smocki (Beyrichia 
Smocki Weller), K. sussexensis (B. sussexensis Weller), K. tuberculata (Beyrichia 
tuberculata Salter), K. wallpackensis (Beyrichia wallpackensis Weller), K. Wailcken- 
sianna (Beyrichia Wilckensianna Jones), K. Wilckensianna plicata (Beyrichia Wilck- 
ensianna plicata Jones). 
Of the above species K. initalis and K. praenuntia are Middle Ordovian and K. 
simplex late Devonian. All the others Silurian. 
The genus Kyammodes Jones is closely allied, distinguished chiefly by the much 
greater inequality of its valves, the thick ventral edge of the right overlapping the 
smaller left valve. There are some peculiar differences in lobation also. 
Tetradella Genotype T. quadrilirata H. & W. 
List of Ordovician species: 
Tetradella ? affinis (Beyrichia affinis Jones), T. bohemica (Beyrichia bohemica Barr. 
MSS. Jones), T. bussacensis (B. hussacensis Jones), T. carinata (B. carinata Krause), 
T. complicata (B. complicata Salter), T. complicata decorata (Beyrichia complicata 
var. decorata Jones), T.? digitata (Beyrichia digitata Krause), T.? digitata separata 
(Beyrichia digitata var. separata Steusloff), T. (Kiesowia) dissecta (Beyrichia dissecta 
Krause), T. 2 erratica (Beyrichia erratica Krause), T. harpa (B. harpa Krause), T. ? 
