280 NATURAL HISTORY. 



primary polypide, and foundation cell of the colony. But before reaching this stage, the embryos pass 

 through a number of phases of development, which, although varying according to the nature of the 

 genus, may be all regarded as derived from a primitive ideal type (Jules Barrois). The wandering, 

 segmented, ciliated, larvae endued with temporary organs of sense, present a remarkable similarity 

 to those of the Brachiopoda, and the pi-esence of a bivalve shell in some species of Bryozoa, as well 

 as the "horseshoe" stage of the loop amongst the Brachiopods, are further embryological points in 

 common. 



The anatomical features of adult individuals of each class are, moreover, very similar. Both the 

 Brachiopod and the Moss-animal breathe and obtain nourishment by means of the pliant, tentaculated 

 organs clothed with cilia which are protruded for that purpose, although the action in the former is 

 constrained by the spiral shape of the fleshy, respiratory, and food -securing organs, and the rigidity 

 of the internal skeleton often supporting them within the mantle cavity. Neither possesses a 

 heart, and the nutritive fluid is circulated entirely by ciliary, or ciliary and muscular action. In 

 both groups a mantle is usually developed, and there is a close identity of type in the structure 

 of the digestive organs, which, among the Brachiopoda, are attached to the inner wall separating 



the body or perivisceral cavity from the mantle chamber by mus- 

 ,,''pi cular bands the equivalents of the funiculus of the Bryozoa. " A 



A certain parallelism may also be suggested between the leading groups 

 of the Bryozoa and the Brachiopods. We have forms like Lepralia, 

 attached by the region of their shells, this shell being calcareous, and 

 exhibiting minute punctures which have been compared to similar 



markings in certain Brachiopods. So among the latter group do we 

 find forms attached, as in Thecidium, and some species of Productus ; 

 and generally the articulated Brachiopods might be compared to such 

 forms as Lepralia (a Sea-scurf) ; while on the other hand such genera 

 as Pedicellina, with its long, pliant, and muscular stalk, or Loxo- 

 soma, with a stalk highly retractile, may be compared to Lingula." 



Fig. 30. A, FREE-SWIMMING CILI- (MorSC.) 



Mft D CH * 1 ^ 08 ' IE LARVA. j j g ev i(j en ^ therefore, from embryological development and 



OF FREDERICELLA. (After Aiiman.) adult organisation, that the Brachiopoda and Bryozoa are so closely 



pi, cuiary piume; pti. Pharynx ; est, stomach; allied as to form a very natural group, and thus are they classed 



cd, Digestive Cavity. * 



by the majority of authors. With regard, however, to the exact position 



in the animal kingdom to be occupied by the group thus restricted, opinions are far less unanimous ; 

 for it is also certain that in their earliest stages of growth the Brachiopoda and Bryozoa betray no 

 molluscan characters. In fact they present such a close resemblance to similar stages of some worms, 

 that such embryological authorities as Steenstrup, Morse, Kowalevsky, and Agassiz, deny their right 

 to admission to the molluscan type. Professor Morse deduced the same conclusion from observations 

 of the habits and structure of full-grown Lingulae. But other zoologists consider these structural 

 affinities merely as throwijLg light on the geological ancestry of both of these coeval types of 

 organisms. 



The literature of the Moss-animals is very copious. I am indebted, among others, to the following 

 standard works : " A History of the British Marine Polyzoa," 1880 (Thomas Hincks) ; " A 

 Monograph of the Fresh-water Polyzoa of Britain " (J. G. Allman) ; " Catalogues of the Species of 

 Marine -Polyzoa in the British Museum " (G. Busk) ; and to the same author's contributions to the 

 "Transactions of the Microscopical Society." For the history of the fossil forms of the class, I am 

 indebted to the well-known works of Alcide D'Orbigny, Jules Haime, and the publications of the 

 Palseontographical Society (G. Busk) ; for anatomical details, to the memoirs of Dr. Arthur Farre, 

 P. J. Van Beneden, Karl Vogt, and T. Hincks, and the works of F. A. Smitt, Nitzsche, Ray 

 Lankester, Morse, Vine, M'lntosh, and Harmer ; and for embryological details, to the complete 

 " Embryologie des Bryozoaires" of Jules Barrois. To the Rev. T. Hincks, M.A., F.R.S., Dr. Jules 

 Barrois, and also to Dr. A. Fritsch, Dr. Kirchenpauer, M. P. J. Van Beneden, and Dr. E. Von 

 Martens, 1 wish to express my thanks for assistance and further information. 



AGNES CRANE. 



