SONNINIA LOCUPLES. 431 



difference — in Sonn locuples |3 the outer lobule of L is strongly bipartite, in Sonn. 

 locuples a the outer lobule is practically entire. The strong bipartition of the 

 outer lobule of locuples |3 is seen to be a feature in another species, Sonn. dominans. 

 In the young Sonn. renovata, however, the bipartition is only incipient — 

 about as much as in locuples a, and not in the same place as Sonn. locuples (5, 

 — though in adult renovata this bipartition is somewhat stronger ; while in 

 Sonn. reformata the outer lobule is distinctly not partite. In Sonn. loculosa, on 

 the other hand, the bipartition is strongly marked, and it is in the same place as 

 in locuples /3 and dominans ; but the outer lobule is altogether shorter than 

 in dominans, so that the agreement is not quite exact. 



Considered, however, in this manner, the species may be arranged in two series 

 at present, with starting-points in the two forms of locuples ; and they may be 

 distinguished thus : 



Sonn. locuples. — Evolute, spinous to bullicostate. 



Two varieties : — a, the outer lobule of L not partite. 

 |3, the outer lobule strongly bipartite. 

 From a, the outer lobule not partite, — 



Sonn. renovata. — Spinous to costate to renewed bullicostate and spinous 



stages. 

 Sonn. reformata. — Spinous to costate. 

 From (5, outer lobule strongly bipartite, — 

 Sonn. dominans. — Involute, costate. 

 Sonn. loculosa. — Involute, subcostate. 

 More particular remarks on the affinities of these species will be found in the 

 following specific articles. 



Sonninia locuples, S. Buchman. Plate XCII, figs. 1 — 4, Plate CIII, fig. 4. 



1892. Sonninia ceassispinata, S. Buchman. This Monograph, Plate L, figs. 16 — 18 



only (and figs. 19—22?).' 



Discoidal, compressed, hollow-carinate. Whorls ornamented with costae and 

 irregularly-placed spines — the costse direct and somewhat reclining, — later with 

 bullicostae, later still with plain, not too conspicuous costse. Ventral area rounded 

 in adult, somewhat flattened, divided by a not very prominent, rounded hollow 

 carina. Inner margin fairly conspicuous, nearly upright. Inclusion about one- 

 third, but not up to the spines except in very early life. Umbilicus open, 

 ornamented with fairly-marked ribs, and not very prominent tubercles. Whorl - 

 1 It is requested that the explanation of the plate be altered in accordance. 



