1886. ] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 551 



The collar-setse are loug aud very stout (figs. 26 and 27). 



The thoracic uncini are like tlie abdominal, but much larger (figs. 



29 and 30). 



The tubes, on their upper surfaces, have two or three very irregular, 

 thin ridges ; their under surfaces, usually attached for the greater part 

 of their" length to dead shells and stones, are, when free, round and 

 smooth. 



Length of large specimen, 16°"". 



Gulf of Mexico, latitude 29° 16' 30" N., longitude 85° 32' W., 26 

 fathoms; station 2369, eight specimens (974). 



PoMATOSTEGUS Schmarda. 



Pomatostegus stellatus Schmarda. 



(Plate xsii, figs. 32-35. Plate xxiii, figs. 36, 37.) 



Terciella stellata Abilclg., Scliriften Natnrf., Freunde, ix, p. 142. 



Serpula stellata Savigny, Syst. des Ann., p. 7.5. 



Pomatostegus stellatus Schmarda, Neue wirbellose Thiere, p. 32, 1859. . 



The opercula have from two to five disks, the upper ones often much 

 worn aud broken, those nearest the peduncle usually quite perfect. 

 The upper disks are readily detached, leaving the projecting stem of 

 the one below surmounted by the usual crown of radial points. The 

 specimens show, in some cases, a partial cleavage of the soft head of the 

 peduncle from the lowest disk (figs. 32-34). It would appear from this 

 that the disks were successively secreted, and that they grow out, 

 keeping the operculum in good repair. 



The coUar-setJB are long and slender, slightly constricted, and then 

 enlarged just below the head of the main shaft (fig. 35). 



The thoracic setfe are limbate; the uncini are large and have twelve 

 or thirteen teeth (fig. 36). The abdominal uncini are the same in 

 shape, but have only nine or ten teeth (fig. 37). 



The branchite are spiral, of little more than one turn. They retain 

 their color in alcohol, varying from a dark blue, with only a trace of 

 white, to a blue with white bands. One specimen has white branchiae 

 with only very narrow bands of blue. 



Length of large specimens, 45™" ; width, 4'°'^. 



Ten specimens (969 and 998). 



Jamaica and Curasao ; shallow water. 



Spirobranchus Blainville. 



Spiiobranchus giganteus (Pall.) Morch. 

 (Plate xxiii, figs. 38-42. Plate xxiv, figs. 43-47.) 

 Serpula gigantea Pallas, Misc. Zool., p. 139, pi. 10, figs. 2-10. 

 Serpula gigantea Savigny, Syst. des Ann., p. 74. 

 Serpula gigantea Grube, Fam. dor Auu., p. 90. 

 Cymospira gigantea Blainville, Diet, des Sci. Nat., Art. Vers. 

 Cymospira gigantea Schmarda, Nene wir'.jellose Thiere, p. 31. 

 Cymospira gigantea Qnatrefages, Hist. Nat. des Ann., tomo ii, p. 543. 

 Spiroiranchua giganteus Morch, Rev. Crit. Serp., p. 56, pi. ii, figs. 18-20. 



