THE SESSILE BARNACLES. 



245 



The second cirri have 10 and 7 segments, anterior rannis longer by 

 about three segments. The segments do not protrude. 



Third cirri simihir to the second, with slightly unequal rami of 11 

 and 10 segments. 



The fourth cirri are longer (fig. 80^). The pedicel is rather long. 

 The anterior ramus has recurved teeth on the anterior margins of the 

 first to tenth segments, varying in number and size as shown in the 

 figures. There are also several smaller, erect spinules near the an- 

 terior distal part of each toothed segment. These segments bear two 

 or three spines, which arise behind the teeth or toward the inner face 

 of the cirrus, except the upper one, which stands on the front margin. 



Fig. 79.- 



-ACASTA CYATHUS FROM ALBATROSS STATION 2146. 

 C, MANDIBLE. 



Q, LABROM. b, MAXILLA. 



Beyond the tenth segment the anterior ramus is similar to the pos- 

 terior, Avhich has no teetli, the segments bearing three to four pairs 

 of spines. 



The individual from near the Dry Tortugas (figs. 80e to li) differs 

 from the preceding by Inning the segments of the fourth to sixth cirri 

 longer, about twice as long as wide. 



The teeth are not so large, and there are three instead of two on part 

 of the segments. There is also some difference in the number of erect 

 spinules, as shown in the figures, although the general arrangement 

 IS not very different. The sixteenth and last toothed segment of the 

 anterior ramus is drawn in figure 80c. 



The largest individuals seen are from St. Thomas, collected by 

 Robert Swift, in the museum of the Academy of National Sciences. 

 Greatest diameter 12 mm., height 11.8 mm. The color is pale pink. 

 The hollow spines are often forked at the end. 



4729°— Bull. 93—16 17 



