. Alaska. Natural history -- Alaska; Scientific expeditions; Alaska. 170 COE The head is continuous with body and provided with four ocelli. Proboscis armature as in other species of Tetrastemma. Habitat. — On piles of wharves, on rocks, among algae, bryozoa, ascidians and other growths. Widely distributed in Northern Hemi- sphere, occurring on the northern coasts of Europe, in the Mediter- ranean and on both the east and west coasts of North America. 14. TETRASTEMMA (CERSTEDIA) RETICULATUM sp. nov. p1. XIV, figs. 7, 8; p1. XX, fig. 7-9. A minute species measuring but 8-15 mm. in length when s

- Image ID: RPXRDA
. Alaska. Natural history -- Alaska; Scientific expeditions; Alaska. 170 COE The head is continuous with body and provided with four ocelli. Proboscis armature as in other species of Tetrastemma. Habitat. — On piles of wharves, on rocks, among algae, bryozoa, ascidians and other growths. Widely distributed in Northern Hemi- sphere, occurring on the northern coasts of Europe, in the Mediter- ranean and on both the east and west coasts of North America. 14. TETRASTEMMA (CERSTEDIA) RETICULATUM sp. nov. p1. XIV, figs. 7, 8; p1. XX, fig. 7-9. A minute species measuring but 8-15 mm. in length when s
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Image ID: RPXRDA
. Alaska. Natural history -- Alaska; Scientific expeditions; Alaska. 170 COE The head is continuous with body and provided with four ocelli. Proboscis armature as in other species of Tetrastemma. Habitat. — On piles of wharves, on rocks, among algae, bryozoa, ascidians and other growths. Widely distributed in Northern Hemi- sphere, occurring on the northern coasts of Europe, in the Mediter- ranean and on both the east and west coasts of North America. 14. TETRASTEMMA (CERSTEDIA) RETICULATUM sp. nov. p1. XIV, figs. 7, 8; p1. XX, fig. 7-9. A minute species measuring but 8-15 mm. in length when sexually mature, and less than 0.5 mm. in diameter. Body short, thick, rounded; much resembling Oerstedia in form and movements, as well as in firmness of body and in general appearance. The peculi- arities of the species are not sufficiently pronounced, however, to warrant its separation from the genus Tetrastemma. Head usually somewhat narrower than body, from which it is usually distinctly marked off by a pair of oblique lateral grooves. These lie opposite the posterior pair of ocelli (p1. XIV, fig. 8), as in related species. Color. — General color of body white, with rec- tangular and longitudinal brown markings vvhich obscure most of the white color of dorsal surface. Two varieties, presenting widely different arrange- /f; Ij I -^1 ment of the dorsal markings, were met with, and Cl' y L'^^l these in extreme cases would suggest two different species. In both varieties the head, which is white or colorless, is provided with a very similar trans- verse deep brown marking between the anterior and posterior pairs of ocelli. This marking consists of a transverse band of color extending laterally some- what beyond the ocelli, and having a rounded and deeply bilobed anterior margin (text fig. 21). It is often shaped like a dumb-bell, except that the contour is straight, and not indented, posteriorly. In the most common variety (p1. xiv, fig. 7) there are about sixteen pairs of

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