SUMMARY PLATE XIV. (continued). 
Arn. Bodleyi, Fig. 27, shows a slightly degenerate compressed whorl, and is the terminal 
form of the subseries containing Hartmanni. 
Arn. kridioides. Fig. 28 gives a view of the transition between Arnioceras and the lowest 
species of Coroniceras. ‘The smooth young straight pile and divergent sides of the adult whorl 
are clearly shown. ‘he artist has exchanged Fig. 8 with Fig. 28. 
Cor. Sauzeanum. Fig. 29 shows the later nealogic and ephebolic stages, having the 
peculiar divergent sides, flattened abdomen, and prominent tubercles of a typical coroniceran 
form. The young, however, still retain the smooth aspect, indicating derivation from Arnioceras. 
Cor. rotiforme. Fig. 30 represents a form similar to Cor, coronaries. 
Cor. Lyra, Fig. 31. This is as a rule much smaller than rotiforme. The sides are more 
convergent, and the whorls more compressed and less numerous than in that species. 
Cor. trigonatum, Fig. 32, exhibits the effects of the premature development of old age 
characters. Fig. 1 on the extreme right shows the dwarfed form of Psil. planorbe, var. leve, 
from which both the arnioceran as well as the agassiceran series may have been derived in 
Central Europe. 
Agas. levigatum. Fig. 33 shows the more compressed variety of this species. 
Agas. striaries, Fig. 34. The striations were too fine to be represented. 
Ast. obtusum. Fig. 2 shows the stouter variety with well marked channels with stout 
gibbous whorls and broad abdomen. This has young almost identical with the adults of the stout 
varieties of Agas. levigatum. 
Ast. Turneri. Fig. 36 shows typical variety, with flattened sides and deep channels, It is 
notably more involute than obtuswm. 
Ast. Brooki. Fig. 37 shows an extreme involute variety of this species, with very conver- 
gent sides and narrow abdomen. The channels are almost obliterated, and the keel very 
prominent. 
Ast. Collenoti. Vig. 38 gives a view of this remarkable dwarfed form, in which degenera- 
tion of the pile and the channels and convergence of the sides have produced morphological 
equivalence with Oxyn. owynotum and Guibali. The amount of the involution is greater than in 
any preceding species of the same series. 
Agas. Scipionianum. Fig. 39 shows the stouter, heavily tuberculated variety, which has 
young almost identical with the stouter varieties of Agas. striaries. 
Agas. Scipionis. Fig. 40 shows an aged specimen in the Museum of Comparative 
Zodlogy, with extremely involute whorls, but keel still prominent, The degeneration of the 
adult as regards the piles and form can, however, be inferred from this figure. The old of 
Scipionianum at the same age is much less changed, and does not exhibit increased involution 
of the whorls. 
Oxyn. oxynotum, Fig. 41, 42. The first figure shows the young of a variety in which at 
an early stage there is close likeness to the young of Agas. striaries, and the adults of Agas. 
levigatum. 
Oxyn. Simpsoni. Fig. 43 shows the stouter form and slightly greater involution of the 
whorls in this species wheu compared with omynotum. 
Oxyn. Lymense. Fig. 44 shows the greater involution of whorls as compared with any 
preceding form of the same subseries, and the very acute degenerate whorl. 
Oxyn. Greenoughi. Fig. 45 shows the stout form of the whorls better defined, and pile 
of this subseries as compared with the oxynotwm subseries. 
Oxyn. Lotharingum. Fig. 46 shows the smaller size of this species, and the degeneration 
of the pile. The involution of the whorls is, however, greater than in any preceding species.’ 
Oxyn. Oppeli. Fig. 47 shows the extremely involute form of the Middle Lias. The stout 
whorls indicate that no great amount of degeneration had taken place. It may have been a 
direct descendant of Greenoughi. 
1 The extreme old age of this form is marked by decrease in the amount of involution of the whorl, and also by 
the loss of the prominent hollow keel. 
