THE Quarterly Journal of Microscopical Science for April 1890 contains papers on Phymosoma varians, Selenka, by Arthur E. Shipley (plates i. to iv.). The material for this paper was collected by Mr. Weldon in the Bahama Islands, where the species was fairly abundant in the soft coral rock. The general morphology and minute structure of this animal are described in great detail, and accompanied by some excellent illustrations; the head of Phymosoma is surrounded by a stiffened vascular horseshoe-shaped lip, the dorsal ends of which are continuous with the ends of a hippocrepian lophophor, which bears a crown of about eighteen tentacles—the number being always even; between this lophophor and the vascular lip is the crescentiform opening of the mouth. The author would keep the genus Phoronis as a form closely allied to the more normal Gephyrea inermia, and compares the head of Phymosoma as seen from above with a view of Phoronis.—On the spinning apparatus of the geometric spiders, by C. Warburton (plate v.). Proves by a series of interesting experiments that a spider's line does not consist of many strands fused or woven together, but ordinarily of two or four distinct threads; the ground line of the spiral is double only, and the two strands are bound together merely by the viscid matter, which envelops them.—On the structure and functions of the cerata or dorsal papillæ in some Nudibranchiate Mollusca, by Prof. W. A. Herdman (plates vi. to x.). In some six gen era of British Nudibranchs examined, Herdman found that the dorsal papillæ, “cerata” of Lankester, were of two kinds—(1) those containing diverticula of the liver, as in the cases of Eolis and Doto, (2) those which were essentially but processes of the body-wall having no connection with the liver, as in Tritonia, Ancula, and Dendronotus. In Doris there are true branchiæ and no cerata. In Ancula both branchiae and cerata are present. In Tritonia and Dendronotus there are cerata but no true branchiæ. In Doto and Eolis there are no true branchiæ. Morphologically all the forms of cerata are probably epipodial processes; they are not of primary importance either in respiration or in digestion, but give to the animals, by their varied shape and colours, appearances which are in some cases protective and mimetic, and in others conspicuous and warning, as may be best suited to the individual surroundings and mode of life.—Further observations on the histology of striped muscle, by C. F. Marshall (plate xi.).—On Chætobranchus, a new genus of Oligochætous Chætopoda, by Dr. A. G. Bourne (plate xii.). This remarkable worm was found in the mud from a “tank” in Madras town; it is furnished with a remarkable series of branchial processes, dorso-laterally placed—a pair to each of the anterior segments, commencing with the second segment; these processes completely surround a portion of the dorsal setæ bundles. The species has been named Chætobranchus semperi.—On the presence of Ranvier's constrictions in the spinal cord of Vertebrates, by Dr. W. T. Porter, of St. Louis (plate xii. bis).—A note to the editor from Prof. Bütschli, of Heidelberg, giving an account of his experimental imitation of protoplasmic movements. These protoplasma-like streaming properties of minute globules of a specially treated olive oil are of extreme interest.