. Bulletins of American paleontology. 390 J. W. Neale and H. V. Howe. Eucytheridea macrolaminata (Elofson) Text-figure 3. Distribution of Eucytheridea macrolaminata (Elofson). group of wide ranging species which show no change in abundance or an abundance which increases southwards, this third category forming a minor element in the fauna. Here we may remark on the absence of typical Loxo- conchidae and Leptocytheridae so characteristic of shelf areas farther south. These are represented in the Barents Sea and other Arctic Seas by rare examples of the two small, tuberculate genera Roundstonia
. Bulletins of American paleontology. 390 J. W. Neale and H. V. Howe. Eucytheridea macrolaminata (Elofson) Text-figure 3. Distribution of Eucytheridea macrolaminata (Elofson). group of wide ranging species which show no change in abundance or an abundance which increases southwards, this third category forming a minor element in the fauna. Here we may remark on the absence of typical Loxo- conchidae and Leptocytheridae so characteristic of shelf areas farther south. These are represented in the Barents Sea and other Arctic Seas by rare examples of the two small, tuberculate genera Roundstonia (ioxoconchid) and Cluthia (leptocytherid) which are fully adult at only about two-thirds the length of typical members of these families and show marked sexual dimorphism. It is uncertain whether Roundstonia globulifcra (Brady), which is represented by a single valve at Russian Harbour, is still living. Cluthia cluthae (Brady, Crosskey, and Robertson) is found at Matochkin Shar and is regarded as a living species. As well as plotting the total population, the adults were plotted separately in the same manner to gauge the effect of juveniles on the abundances. This had two main effects. Firstly, it modified the order of abundance in the case of some of the larger forms, particularly noticeable in the case of Robertsonites tuberculata which had a large number of juveniles present at the time the sample was taken. Secondly it increased the relative proportions of the smaller species such as Semicytherura undata (Sars), S. concentrica (Brady, Crosskey and Robertson), Xestoleberis depressa Sars, and Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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