Mr. H. J. Carter on the Classification of the Spongida. 177 close to the end of the Liparidre, I overlooked it when formerly working at the group, and therefore described the species as an aberrant Pericopis. I have to thank Mr. Stretch, of San Francisco, for directing my attention to this genus and to Sermyla of Walker. The late Dr. Herrich-Schaffer, in the Correspondenz-Blatt zoolog.-min. Ver. Regensb. vol. xx. p. 131 (1867), described a species of Pericopis from Cuba, under the name of P. cubana ; but all the diagnoses in that paper are so abbreviated as to be incomprehensible to me, so that I cannot attempt to determine its position. The present group may be conveniently followed up by Hypercompa (or Callimorpha) , the white-winged species form-ing a convenient transition to the typical Arctiidae. XXIII. — Notes Introductory to the Study and Classification of the Spongida. By H. J. Carter, F.R.S. &c. [Continued from p. 145. J HOLORHAPHIDOTA. Family 1. Renierida. Groups 1-4. Amorphosa, Isodictyosa, Thalyosa, and Crassa. Sarcode colourless, pale tawny, or dark brown. Skeleton consisting of spiculo-fibrous reticulation filled up with areolar flaky sarcode, like crumb of bread when dry. Fibre composed of spicules held together by a minimum of sarcode ; areolar sarcode charged with the spicules of the species and ampul-laceous sacs. Surface even, for the most part covered, with a fine dermal reticulation like that of the Rhaphidonemata ; some-times without any, and then cancellous. Colour pale tawny, dark brown or white, when dry. Vents large, distinct, scat-tered, on a level with the surface, or more or less projecting on mammiform or mamillary prolongations of the sponge when external ; or on a level with the cloacal surface in the tubular or excavated specimens — that is, when internal. Branched excretory canal-system generally well pronounced. Pores in the sarcode which tympanizes the interstices of the dermal reti-culation. Spicules of one kind only, viz. the skeleton-spicule, for the most part consisting of a simple acerate, long or short, thick or thin, finely or abruptly pointed shaft varying with the species ; or cylindrical, curved, round at the ends sausage-like, of various sizes in the same specimen. Forms incrusting or massive, solid or excavated, or branched ; branches solid.
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