Hyatt.] 14 [November 1, 



was wholly embryological, the sponges were one of the three largest 

 divisions, equivalent, in fact, to the whole of the remainder of the 

 Animal Kingdom, except Protozoa. Huxley had no intention what- 

 ever of showing that the sponges were a new sub-kingdom, or in any 

 sense equivalent to such divisions as are usually represented by 

 that term. MacAllister has really done this, and to him the credit 

 is due of having first shown that the sponges are the equivalents, 

 from a structural point of view, of the Vertebrata, or Arthropoda, or 

 Radiata, taking those names in their broadest sense and application. 

 This service is of real value as an advance in classification, and 

 though it is accompanied by an almost wholly erroneous statement of 

 the characteristics of the structure, due to the authorities from which 

 the quotations are taken, it must receive due credit, as the first re- 

 corded estimate of the proper place of the sponges in our system of 

 classification. 



Special studies upon the structure of the full grown sponges first 

 led Mr. Hyatt, somewhat more than a year since, to view them as dis- 

 tinct from the rest of the Animal Kingdom. This view, however, was 

 kept back until such a knowledge of the embryology could be obtained 

 as was necessary to prove, or disprove, as the case might be, their 

 supposed connection with the Protozoa on the one side, and the Corals 

 on the other. This idea was originated independently, since it was not 

 until fully convinced of this fact, that he saw Huxley's, and subse- 

 quently MacAllister's paper; the observation, therefore, has the value 

 of an independent investigation. In fact, an article was written for 

 Johnson's Encyclopedia, of which the proof has not yet been received, 

 in which no mention is made of MacAllister's or Huxley's views. So 

 far as their separation from the Protozoa is concerned, Huxley has 

 shown that they differ in the production and subsequent segmenta- 

 tion of a true unicellular egg; but his idea based principally upon 

 Hasckel's observations, that they are polystomatous, or that the 

 cloacal openings can be in any way homologized with the mouth 

 opening in other animals, especially polyps, because it is found in 

 the gastrula form in embryo, and is maintained subsequently through- 

 out life, has been shown to be without foundation. Carter and 

 Barrois' researches both show, that the only opening which can be 

 be compared with the mouth of the gastrula form is usually the base 

 of the sponge; and the latter, as described above, that the cloacal 

 opening occurs by a breaking through of the ectoderm after the canals 

 are formed in the endoderm. In fact, he goes so far as to attribute its 



