204 POLYDORA CILIATA. 



seventeen bristled feet, the increased number of eye-specks in the earlier, and their 

 diminution to four in the last stage, the appearance of tentacles, the presence of four 

 rows of stellate pigment-specks on the dorsum of the segments, the development of 

 branchiae on the seventh and succeeding segments, the last stage (seventeen feet) having 

 five, the formation of the terminal sucker with its dorsal hiatus, the disappearance of 

 the jointed larval bristles, the growth of the capillary bristles and hooks, and the forma- 

 tion of the bifid prow to the cephalic region, are the most noteworthy features. It has to 

 be stated, however, that Claparede saw no change in the fifth bristled segment in his 

 young form, whereas De St. Joseph describes and figures these as present in an example 

 of the same size (seventeen setigerous segments). There is thus uncertainty as to the 

 identity of Claparede's species, unless he had overlooked the fifth segment. 



Cunningham and Ramage (1888) seem to doubt the ability of this well-known 

 boring form to penetrate the shells of oysters. As, however, they mentioned that they 

 found it in chinks and clefts of rocks it is possible P. flava is referred to. They describe 

 the nephridium as arising from an internal aperture beneath a glandular sac, as mentioned 

 by Claparede, that it is thereafter reflected on itself, and then " passes to open to the 

 exterior near the dorsal median line." The nephridium in their form contained black 

 granular matter. 



De St. Joseph 1 (1894) describes and figures a young stage of seventeen setigerous 

 segments with touches of violet on each, six eyes, and developing tentacles. The large 

 hooks occur on the fifth segment, and glands are present from the sixth to the twelfth 

 segment, whilst the anal cup resembles that of the adult. 



It is doubtful if the Polydora cseca of De St. Joseph 2 (1894) refers to P. ciliata, 

 though the figure of the head as given by him may be indifferent. This author figures 

 and describes a young example of P. ciliata of about twenty segments. 



In going over the single example of the so-called Polydora Giardi of Mesnil — kindly 

 forwarded by Major Elwes— the following points have been noted : The specimen is a 

 small one, viz. about a quarter of an inch in length, and Mesnil observes that it is always 

 slender and small as compared with others. The head is devoid of pigment, though, if a 

 young form, such might be expected. No eyes are visible — whether these are absent in 

 the young P. ciliata is not noted, but they are irregular even in adults. A distinction is 

 the occurrence of branchiae on the tenth segment instead of the seventh as in P. ciliata. 

 These branchiae in P. ciliata reach thirty-one in number. Now, Mesnil observes that in 

 P. ciliata they extend far backward, and that only the last ten segments are devoid of 

 them, whereas in P. Giardi they disappear about the twenty-fifth setigerous segment, so 

 that the branchiae of his ciliata differ from the British, whilst those of his Giardi agree. 

 Mesnil says there are two to four very small dorsal bristles in the first foot. This is not 

 an important feature. In the example three were on one side and six on the other. The 

 same may be said of the group of the dorsal bristles behind the fifth. The hooks 

 commence on the seventh segment as in P. ciliata. Mesnil thinks they differ from those 

 of P. ciliata and other forms, but so far as the small example goes they do not appear to 

 differ from those of P. ciliata except in size. Mesnil admits that the great hooks of the 



1 ' Ann. Sc. nat./ 7 e ser., t. xvii, p. 63, pi. iii, fig. 73. 



2 Ibid., 7 e ser., t. xvii, pi. iii, figs. 65—70. 



