Mr. H. J. Carter on a Lacustrine Bryozoon allied to Flustra. 1 69 of fibres ; each fasciculus is twisted together near its centre; these, some of them being larger than others, star the structure thickly, and still more plentifully where the white excrescences appear. I am not prepared to state that this case was built by the animal, and some have suggested that it may be one of the Medusce ; but the microscopic structure appears to negative this latter idea. That it is the nest in which the animal dwelt appears certain, but how it was constructed we have no information to guide us ; still it is not at all improbable that there are many processes in the lower forms of life that have not yet been made known, some of which may be even more astonishing than the supposed fact, that an animal whose constant habit is to dwell within the protecting walls of another, can, upon being expelled by accident from its usual abode, secrete a substance that will protect it from external injury, and, as far as may be, fulfil the conditions of its normal position. EXPLANATION OF PLATE VIIL Fig. 1. Case of Siphonocetus typicus, enlarged (after Kroyer). Fig. 2. Tubes of Siphonocetus crassicornis on Antennularia, enlarged. Fig. 3. Nests of Podocerus pulchellus on Laomedea, enlarged. Fig. 4. Nests oi Podocerus fucicola"? on Ulva and Tubularia. Fig. 5. Nests of Amphitoe rubricata at the root of Laminaria. Fig. 5 a. Microscopic structure of the same. Fig. 6. Supposed nest of Phronima. *Fig. 6 a. Microscopic structure of the same. XVII. — Description of a Lacustrine Bryozoon allied to Flustra. By H. J. Carter, Esq., H.C.S. Bombay. [With a Plate.] The following is a description of a polypidom which was sent to me by the Rev. S. Hislop, who found it for the first time in April last, growing plentifully on Paludina Bengalensis and the stems of aquatic plants, in a freshwater tank and adjoining well at Nagpoor, in Central India. So far as I am aware, it will form the first on record of a freshwater species of this kind of Bryozoon ; and being encrusting and without calcareous matter in the skeleton, it will also afford the type of a new genus at least, for which I propose the name Hislopia, in honour of the reverend gentleman above mentioned, to whose acute observation and intelligence we are indebted not only for its discovery, but, in conjunction with his late colleague, the Rev. R. Hunter, for
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