From these figures it appears that the Kokomo forms had cephala which were much more nearly square than rectangular. A set of comparative figures for the proportions in the different parts of the three species brings out the differences clearly.
| Lengths in millimeters | ||||||
| species | carapace | preabdo- men |
postabdo- men |
telson | ratio of cara- pace to rest of body | |
| E. scorpionis | 31 | 40.4 | 56.0 | 53.0 | 20.7:100 | |
| E. ranilarva | 35 | 40.0 | 50.0 | 35.0 | 27.8:100 | |
| 33 | 43.5 | 41.5 | 36.0 | 27.0:100 | ||
| E. kokomoensis | 28 | 32.3 | 43.4 | 30.4 | 25.9:100 | |
The same relations hold here between the body proportions of the Kokomo and Bertie species as held in the case of Eusarcus. A comparison of the figures for E. dekayi and the first specimen of E. ranilarva shows that though the carapace of the latter is longer, all of the other parts of the body are shorter. Thus, the Eurypterus species as well as the one of Eusarcus are relatively shorter and broader forms than the ones found in the Bertie.
The Kokomo eurypterid fauna as a whole is quite distinct from any other American fauna, a fact which is difficult to explain on the theory of marine habitat for these organisms. If, as Clarke and Ruedemann have stated, the Kokomo is of Lockport age, and belongs to the marine fauna of that time, it is greatly to be wondered at that there should be no eurypterid fauna in the succeeding Guelph beds in the same locality or in adjoining regions. Yet the only Guelph form that has ever been found is the single specimen of Eurypterus (Tylopterus) boylei from Ontario, a form which shows not the slightest resemblance to any of the Kokomo eurypterids. If the Kokomo is to be considered of Monroan age, for reasons which have been given in full on p. 118 then, on the marine theory, the Kokomo forms should show relationship to the Bertie, and their area of deposition should constitute merely another "pool" cut off from the Monroan sea. But it has just been shown that the Kokomo fauna is quite distinct from the Bertie and that the two faunas have no species in common, a fact difficult to explain on the ground that the forms lived in neighboring "pools" where faunas were segregated from a once widespread marine fauna.
