The general structure of the polypides or zooids was, in many respects, accurately described, 

 particularly so far as concerned the external characters, the aHmentary canal and the ovaries. 

 The selection of the specific name, dodecalophus, in alkision to the existence of six pairs of 

 tentacuHferoLis arms, proves to have been fortunate, since the examination of the "Siboga" 

 material shews that the number of the arms is an important specific character. The description 

 of the remarkable pigmented oviducts as eyes is a mistake which is a natural one to have 

 made, in consequence of the eye-like appearance presented by these bodies in an external view 

 of the zooid. 



The article "Polyzoa" written by Professor E. Ray Lankester for the "Encyclopaedia 

 Britannica" (85) contains the first figures which were pubhshed of CepJialodisais^ these being 

 taken from original drawings supplied by Professor M'Intosh. The position of RJiabdopleura 

 and Cephaiodiscus as a Section of the Polyzoa is here delinitely formulated. 



M'Intosh published his "Challenger Report" in 1887, and at the end of that Report 

 appeared an Appendix in which I was able to demonstrate the close affinity of Cephaiodiscus 

 to Balanoglossus '). This view was disputed by Ehlers in 1890 (p. 164), while in the same 

 year Lang provisionally accepted it in a paper (90) written to shew that the differences between 

 Cephaiodiscus and Balanoglossus were in the main due to the fact that Cephaiodiscus has taken 

 on a sessile and tubicolous form of life, resulting in the forward migration of the anus and in 

 other departures from the arrangement of the organs found in Enteropneusta. 



At the close of his great Monograph on the Enteropneusta of the Gulf of Naples, 

 Spengel (93, p. 753), as the result or his own investigation, expresses his concurrence with the 

 view that Cephaiodiscus is related to Balanoglossus. 



In 1896 — 1899 appeared a series of papers by Masterman, who in several important 

 respects extended our knowledge of the structure of Cephalodisctis. Masterman was the first 

 to describe the vascular system and the details of the budding processes, while he added 

 considerably to what was known of the nervous system. I shall have occasion to discuss 

 Masterman's results in the later portions of this Report. I ventured to criticize some of them 

 in a note published in 1897, in which year Spengel (97) also published a few remarks on 

 the same subject. 



In 1899 appeared a paper by Cole on the terminal swellings of the tentaculiferous arms 

 of Cephaiodiscus. These, which had been regarded by Masterman as compound eyes, were 

 described by Cole as having a structure similar to that of the rhabdite-cells of Planarians. 



In 1903 Masterman published a further paper on Cephaiodiscus^ dealing with the structure 

 of the "central complex", or region of the proboscis-stalk and adjacent parts. 



The whole of the literature mentioned so far was based on the examination of the 

 original "Challenger" material; that is to say, on female specimens of C. dodecalophus. 



In 1903 Andersson announced the discovery, by the Swedish Antarctic Expedition, of 

 specimens of Cephaiodiscus^ in four dredgings taken in the neighbourhood of the Falkland Islands. 

 The depths ranged from 80 to 235 M. In the absence of a fuller account of the discovery, it 



l) I heie use this namo in its older sensc as including all the species of Enteropneusta, now airanged in a series of genera 

 by Spengel (oi). 



