42 OONKLIN — EMBRYOLOGY OF A BRACHIOPOD. I April 4, 



American naturalist, Prof. E. S. Morse ('71- 73)- How thorough 

 and complete this work was I shall have occasion to remark in the 

 further course of this paper ; but done as it was at a time before 

 good microtomes and imbedding means were invented, and long 

 before serial sections were thought of, it could not but leave much 

 of the internal structure of the embryo undetermined, especially as 

 the eggs and embryos of the form studied (^Terebratulina sep- 

 tentrionalis) are quite small and opaque. Nevertheless Morse's 

 work stands to-day as one of the two most important works on the 

 embryology of the brachiopods. The other work referred to is the 

 later but more detailed and comparative ** Observations on the 

 Development of Brachiopods," by the great Russian zoologist, 

 Alexander Kowalevsky (1874). Kowalevsky's work, which was 

 published in Russian, remained practically unknown to those not 

 acquainted with that tongue until 1883, when Oehlert and Deniker 

 published an excellent abstract of it. In this work Kowalevsky 

 describes his observations on the development of four species — 

 Argiope {^Ciste/la) 7ieapolitana, Thecidium mediterraneum, Terebrat' 

 ula fni?W7' and Terebratulina caput-serpentis; only a few observations 

 were made on the development of the two last- mentioned species, 

 but his work on Cistella and Thecidium was detailed in character 

 and nearly complete so far as the stages of development are con- 

 cerned. Although Kowalevsky employed isolated sections to a 

 limited extent in his work and also shows certain details of internal 

 structure in many figures of entire embryos, yet his work of neces- 

 sity left many important problems of structure unsolved. 



In 1879 Prof- ^ • K. Brooks discovered the free- swimming larvae 

 of Linguia {Glotlidid) pyramidata and described in detail the 

 structure and further development of these larvae up to the adult 

 condition. This work, although dealing only with the larval stages 

 and metamorphosis, is still the most complete extant on the devel- 

 opment of the Ecardines, the most primitive group of the brachio- 

 pods. With characteristic insight Brooks has used his many 

 important discoveries on the later development of Glottidia in an 

 extremely valuable discussion of the systematic position of the 

 brachiopods. 



The small portion of Shipley's (1883) paper on Argiope {Cistella) 

 which treats of the development of that form adds little to the 

 much more extensive work of Kowalevsky on that animal. His 

 principal contribution consists in his determination of the fact that 



