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

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

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

 tentaculiferous 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 L.vnkestf.r for the "Encyclopaedia 

 Britannica" (85) contains the first figures which were published of Ceplialodiscus, these being 

 taken from original drawings supplied by Professor M'Intosii. The position of Rhaddopieiira 

 and Ccplialodlscus as a Section of the Polyzoa is here definitely formulated. 



M'Intosh published his "Challenger Report" in 18S7, and at the end of that Report 

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

 to Balanoglossus '). This view was disputed by Ehlers in 1 890 (p. 1 64), while in the same 

 year L.\ng provisionally accepted it in a paper (90) written to shew that the differences between 

 Cephalodiscus and Balanoglossus were in the main due to the fact that Cephalodiscus 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, 

 Si'ENGEL (93, p. 753), as the result or his own inve.stigation, expresses his concurrence with the 

 view that Cephalodiscus 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 Cephalodiscus. 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 jjortions of this Report. 1 ventured to criticize some of them 

 in a note published in 1897, '■'' which year Spexgel (97) also published a few* remarks on 

 the same subject. 



In 1899 appeared a paper by Cole on the terminal sw^ellings of the tentaculiferous arms 

 of Cephalodiscus. 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 MasternL'VN published a further paper on Cephalodiscus, dealing with the structure 

 of the "central complex", or region of the jiroboscis-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. dodccalophus. 



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

 specimens of Cephalodiscus, in four dredgings taken in the neighbourhood of the b'alkland Islands. 

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



l) I here ii>i" ihis n:um: in it-i .iltler ^en-it' :>^ including all the species of Enteropneusta, now arranged in a series of genera 

 l)y Spe.\gel (01). 



