. Fig. 104. 2nd and 3rd joints of peraeopod 3 of Epimeria viewed obliquely from behind: a. inermis, Wlkr. b. acanthurus, Schell. c. intermedia, Schell. , Brnrd. e. excisipes, (In d the faintly dotted line indicates the bottom of the channel formed by the inner and outer keels.) These are mostly large forms and hence are amenable to a somewhat closer scrutiny than many smaller forms. Thus in the study of the Discovery material I have become aware of one feature which would seem to be of considerable value in diagnosing the species. Unfortunately the three species in the Terr
. Fig. 104. 2nd and 3rd joints of peraeopod 3 of Epimeria viewed obliquely from behind: a. inermis, Wlkr. b. acanthurus, Schell. c. intermedia, Schell. , Brnrd. e. excisipes, (In d the faintly dotted line indicates the bottom of the channel formed by the inner and outer keels.) These are mostly large forms and hence are amenable to a somewhat closer scrutiny than many smaller forms. Thus in the study of the Discovery material I have become aware of one feature which would seem to be of considerable value in diagnosing the species. Unfortunately the three species in the Terra Nova collection were so clearly differentiated on the more obvious features that the detail to which I am here drawing attention did not obtrude itself. That, however, is of little consequence as two of those species occur in the Discovery collection, and it is only robusta that I am not able to include in the following comparison. The 2nd joints of peraeopods 3-5 have participated to a greater or lesser degree in the general induration of the integument in these forms, for the purpose of closing the gap between the 4th and 5th side-plates and the pleura of the pleon segments when the animal is curled up. They thus become available for the development of rib-like strengthening keels, marginal flanges and spiniform projections.
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Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
