Journal of conchology . 5-— vet Fig. 2. — Larva of Dreissensia, looking down Fig. 3. —Older larva of Dreissetisia, with from above upon the velum, which is velum greatly expanded, seen from fully expanded; /, pigmentation of the side; ?«, retractor muscles of the the velum (7t/.) ; ^/, pigment beneath velum (iieL); pi, pigment; s, the the oral opening; s, shell, which is two valves of the shell (from Kor- for the most part concealed by the schelt, 92).velum. together and the larva sinks to the bottom until the danger is larvse swim in large numbers on the surface of the water, and
Journal of conchology . 5-— vet Fig. 2. — Larva of Dreissensia, looking down Fig. 3. —Older larva of Dreissetisia, with from above upon the velum, which is velum greatly expanded, seen from fully expanded; /, pigmentation of the side; ?«, retractor muscles of the the velum (7t/.) ; ^/, pigment beneath velum (iieL); pi, pigment; s, the the oral opening; s, shell, which is two valves of the shell (from Kor- for the most part concealed by the schelt, 92).velum. together and the larva sinks to the bottom until the danger is larvse swim in large numbers on the surface of the water, and Iwas able to capture many in the canal at Newsham, near Preston, byusing a very fine net, on a perfectly calm and very hot June day. Theyare, however, so very small that it is easy to mistake them forrotifers—especially if the zone of cilia happens to be in active motionduring examination. Dr. Korschelt, in the course of his remarks, says:—The chiei 8s JOURNAL OF CONCHOLOGY, VOL. II, NO. 3, JULY, 1904. features in the
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Keywords: ., bookauthorconcholo, bookcentury1800, bookdecade1870, bookyear1879
