Notes on the Ffnml// Cathypnida'. By J. Murray. 551^ 



tessellation is on the same general plan as that of C. stokesii, 0. 

 ploenensis, etc. The toes are slender, slightly enlarged at ])ase, 

 hardly tapering except near the acute points. 



Studied from specimen in Mr. Eousselet's collection. 



Cathypna sfokesii Pell (JS). Plate XXIII, figs. 12^/-12e. 



Description. — Of medium size, oval. Dorsal plate broader, 

 tessellated, anterior margin convex, between prominent spines, 

 ventral margin excavate in a flat V. Posterior lobe produced into 

 a forked process : toes slender, of moderate length. 



Length of contracted lorica 125-135 yit, of dorsal plate 100 /jl, 

 of toe 45 fjL ; breadth of dorsal plate 75 fi, of ventral plate Q^j jjl, 

 of anterior border 50 yn. 



The faceting is of the pattern commonest in the family, as in 

 G. ploenensis (fig. 4«), C. ohioensis (fig. 14a), etc. The anterior 

 margin is nearly straight, flatly convex (fig. 12a), or broken into 

 three short convex sections (fig. 12c). The toe is expanded at the 

 base, then scarcely tapering till near the acute point. 



The American form (fig. 12c), has the posterior processes straight 

 and acute. The English form (fig. 12a) has them slightly incurved, 

 shorter, and less acute. I can see no other differences between the 

 two. 



I have drawn the American variety from specimens in Mr. 

 Eousselet's collection, the English form from a specimen given me 

 by Mr. Stevens of Exeter, who discovered it in this country. 



Cathypna mira sp. n. Plate XXII, fig. 3. 



Specific Characters. — Of medium size, pyriform. Dorsal plate 

 broader, oval, truncate at both ends, the lateral border reaching to 

 frontal margin, but curved downwards again. Anterior margin 

 straight, between short broad spines. Posterior lobe of lorica very 

 prominent. Toes short, shouldered and clawed. Faintly faceted 

 dorsally on an unusual pattern, and punctate. 



Description. — Length of contracted lorica 130 fx, of dorsal plate 

 100 /A, of toe 85 /x; breadth of dorsal plate 94 /i, of ventral plate 

 80 fjb, of anterior border 60 jx. 



The dorsal margin is very unusual in merely touching the 

 anterior edge and curving away from it again. The pattern of the 

 dorsal faceting is quite peculiar, having median facets where other 

 species, such as C. ploenensis (see fig. 4a), have pairs, and vice 

 versa. The facets are almost flat, not separated by ridges. The 

 anterior spines are broad, with a sigmoid curvature on the inner 

 side. In the figure the dots are shown only on a few of the facets, 

 in order not to obscure the pattern. 



