. The Cambridge natural history. Zoology. TENTACULATA—LOBATA 419 multicornis. These tentacles have no sheaths, and do not bear pinnae. They are probably not homologous with those of other Ctenophora. The characters that separate the families of Lobata are chiefly those of varying size, shape, and position of the peristomial lobes and auricles. In the Lesueuriidae the peristomial lobes are rudi- mentary ; in the other families they are moderately or very large. In the Bolinidae the auricles are short, but in most of the other families they are long and ribbon-like. In Eucharis they can be spira
. The Cambridge natural history. Zoology. TENTACULATA—LOBATA 419 multicornis. These tentacles have no sheaths, and do not bear pinnae. They are probably not homologous with those of other Ctenophora. The characters that separate the families of Lobata are chiefly those of varying size, shape, and position of the peristomial lobes and auricles. In the Lesueuriidae the peristomial lobes are rudi- mentary ; in the other families they are moderately or very large. In the Bolinidae the auricles are short, but in most of the other families they are long and ribbon-like. In Eucharis they can be spirally twisted in repose. The modifications of the external form seen in the Lobata are accompanied by some modifications of the internal structure Among these, perhaps the most interesting is a communication between the transverse longi- tudinal and the para- gastric canals, and the long convoluted tubes given off to the peri- stomial lobes by the sagittal longitudinal canals. Very little is known about the life- history and development of most of the Lobata, but Chun has shown that in JSucharis and JBolina there is a Cydip- piform larval stage which produces ripe ova and spermatozoa. This is followed by a period of sterility, but when the adult characters are developed they become again sexually mature. To this series of sexual pheno- mena the name " Dissogony " i% given. The order contains only fifteen genera, but they are usually arranged in the following eight families:— 1. Lesueuriidae. Zesueuria. 2. Bolinidae. Bolina, Bolinopsis. 3. Deiopeidae. Beiopea. 4. Eurhamphaeidae. Fig. \%\. — Ocyroe crystcdlina, Ab, aboral sense- organ ; au, auricle ; Oan, diverticulum from the paragastric caiial passing into peristomial lote ; Ct, eostae ; M, mouth ; Par, paragastric canal passing outwards to jdin one of the transverse subcostal canals ; , peristomial lobe ; w, wart- like tubercles on the lobe. (After Mayer.). Please note that these images are
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
