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. 



