. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. COE: NEMERTEANS OF WEST AND NORTHWEST COASTS. 213 44. Zygonemertes thalassina Coe. Proc. Wash. Acad. Sci., 3, p. 29, PI. 2, fig. 5 ; PL 7, ; PI. 13, fig. 2, 1901; Harriman Alaska Expedition, 11, |.. 29, 1904. Text-figs. 17, 34, 35. The very active and restless worms belonging to this species and the closely related Z. virescens may be easily recognized by their olive green color, and by the ocelli which are very numerous on each side of the head, and which extend posteriorly along the lateral nerve cords far beh
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. COE: NEMERTEANS OF WEST AND NORTHWEST COASTS. 213 44. Zygonemertes thalassina Coe. Proc. Wash. Acad. Sci., 3, p. 29, PI. 2, fig. 5 ; PL 7, ; PI. 13, fig. 2, 1901; Harriman Alaska Expedition, 11, |.. 29, 1904. Text-figs. 17, 34, 35. The very active and restless worms belonging to this species and the closely related Z. virescens may be easily recognized by their olive green color, and by the ocelli which are very numerous on each side of the head, and which extend posteriorly along the lateral nerve cords far behind the brain. Mature individuals are very slen- der, and are usually from 80-60 mm. in length. The proboscis sheath reaches to the posterior end of the body, but the proboscis itself is but little more than half as long. The central stylet of the proboscis is remarkably short and blunt; its basis is at least twice and often three times as long as the stylet itself, and is massive in pro- portions (Text-fig. 84). The basis is sharply truncated posteriorly, with serrated edges. Each of the two lateral pouches usually contains five remarkably stubby accessory stylets (Text-fig. 35). There are 12 probos- cidial nerves. In Z. virescens the stylets are more slender, commonly but 2 or 3 in each lateral pouch, and the proboscis has but 10 or 11 nerves. Habitat.— This species has been found only at Sitka, Alaska, where it is not uncommon among hydroids, broken shells, etc., in clear water (Coe, :01). The only decided differences that I have been able to determine between this species and the closely related Z. virescens of the Cali-. FiG. 34.— Zygonemertes thalassina. Outline of apparatus of pro- 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 Harvard University. Museum of Comparative Zoology. C
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