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THE AMERICAN NATURALIST. [Vol. XXXVII. 



material for the first investigation ever undertaken of the entire devel- 

 opment of a brachiopod, and is a very careful reinvestigation of the 

 early stages of this species by the aid of modern methods of prepara- 

 tion and microscopical technique. The early cleavage forms are 

 found to present considerable variation, commonly in the produc- 

 tion of very unequal divisions. These forms do not especially 

 resemble those of the molluscs and annelids, but are more like those 

 of the Bryozoa and Phoronis. Gastrulation is by invagination. The 

 suggestion is offered that certain deep-staining granules seen at 

 the free ends of the gastrula cells are associated with the cilia of the 

 embryo. The archenteron at first possesses one constriction instead 

 of two as in Cistella. The proper orientation of the embryo shows 

 that it belongs to the hypogastric type, an important difference from 

 the Chajtognatha with which the Brachiopoda are sometimes sup- 

 posed to present close relationship. The larva shows three regions, — • 

 cephalic, mantle, and peduncular, which, however, are not true seg- 

 ments. The mantle at first covers the peduncular region and is sub- 

 sequently folded up over the cephalic portion. Dr. Conklin compares 

 the embryo of Terebratulina with the trochophore and with the 

 embryos of Phoronis and the Bryozoa, and concludes that the two 

 latter groups and the Brachiopoda should go together in a single 

 phylum, and that their relations with the Chrctopoda and Chretog- 

 natha are not especially close. 



" Observations on living Brachiopoda" by the veteran student of this 

 class, Prof. E. S. Morse, 1 is a timely contribution to a much neglected 

 subject. Occasional references to the habits of brachiopods may be 

 found in various works, as those of Davidson, CEhlert, Woodward, 

 etc., but Prof. Morse's paper contains by far the most extensive and 

 valuable series of observations on the subject yet published. The 

 title, however, does not convey an adequate idea of the extent of the 

 work, for the author has given a large amount of anatomical detail, 

 especially in regard to the mesenteries and perivisceral bands, sense 

 organs, "hearts of Hancock," accessory hearts, etc., which is not 

 confined to observations on the living object. The species chiefly con- 

 sidered are : Glottidia pyramidata, Lingula lepidula, and L. anatina, 

 though in addition observations have also been made upon Discinisca 

 lamellosa, and D. stella, Terebratulina septentrionalis, Terebratalia 

 coreanica, T. minor, Laqueus rubellus, Hemithyris psittacea, H. a/bida, 

 and Dallina grayi. The tenacity of life in brachiopods, especially 



Hist., vol. 5, No. 8, pp. 3U-386, pis. 39-61, July, 1902. 



