. Bulletin - United States National Museum. Science. 26 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. cells (fig. 12, D). Later these gather again into the limbs of the horse- shoe, which become enlarged and entirely distinct from each other (F). The third change is the formation of the plug of optic cells, which arises by the tip of the arch of the horseshoe curling over backward (fig. 12, C) and later becoming the almost inde- pendent mass of cells figured (E, F, and pi. 2, figs. 7 and 8). For more adequate description of the structure and develop- ment of the ganglion and eyes of Cyclo- salp
. Bulletin - United States National Museum. Science. 26 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. cells (fig. 12, D). Later these gather again into the limbs of the horse- shoe, which become enlarged and entirely distinct from each other (F). The third change is the formation of the plug of optic cells, which arises by the tip of the arch of the horseshoe curling over backward (fig. 12, C) and later becoming the almost inde- pendent mass of cells figured (E, F, and pi. 2, figs. 7 and 8). For more adequate description of the structure and develop- ment of the ganglion and eyes of Cyclo- salpa pinnata see Metcalf (1893, c). The neural glands are similar in the solitary and aggregated Fig. 13.—Cyclosalpa pinnata, SUBSPE- CIES POLAE, SOLITARY FORM, DORSAL view. From Sigl (1912, a). CYCLOSALPA PINNATA, subspecies POLAE (Sigl) (1912). Cyclosalpa polae Sigl (1912). This subspecies is said by Sigl to be dis- tinguished by two features: first, in the solitary individuals, the fusion of body muscles VI on the dorsal mid line and their continuance forward as a median muscle band reaching almost to the level of body muscles II (fig. 13); and, second, the long peduncle by which the aggre- gated zooids are united to form the wheel (fig. 14). In the collections of the United States National Museum submitted to us are three specimens of the solitary Cyclosalpa pinnata which are of the subspecies polae. One is 17 mm. long; one is 7 mm. long; the third is an embryo 8 mm. long, in which the placenta is present. None of them show any peculi- arity beyond the pres- ence of the median dorsal extension of body muscles VI. In the same bottle, and of course from the same place of collection, is fig another solitary indi- vidual 24 mm. long, of the usual pinnata character. There are also S aggregated zooids 14 mm. long, four of them still attached together in a broken wheol, and 2 aggregated zooids 11 mm. long, not attached. M+JZ Please note that these images are extr
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