SERPULIDAL. 327 
on the structure of the opercula, and, in the case of Protula, on the spiral arrangement of the 
branchie, or the fan-like nature of the branchie in Psygmobranchus. These data were 
insufficient, and consequently considerable confusion resulted. Thus, for instance, his 
genus Vermilia included six new species, and of the two known forms, one was the common 
Pomatocerus triqueter, and the other was probably synonymous with the ubiquitous 
Serpula vermicularis, entered, as also was the former, under another genus. 
Morch! (1861-63), in his ‘ Revisio Critica Serpulidarum, has about 135 species of 
Serpulids under 16 genera, Spirorbis having no less than 27, Hydroides 17, Serpula 14, 
Vermilia 12, Protula and Placostegus each 11, Ditrypa 8, and the others smaller numbers. 
This list could be considerably reduced almost under every genus. 
Dr. Johnston’ (1865) enters 10 species of Serpulze in the body of the work, and in 
the Appendix Dr. Baird added another and no less than 17 species of Spirorbis from the 
literature on the subject, but in both cases the number needs substantial reduction, since 
some appear under two or three titles. 
De Quatrefages*® (1865) mentions about 109 species as occurring throughout the ocean, 
but it 1s evident that many are synonymous, and that the series could be much reduced. 
Twenty species are recorded by Malmeren‘ from the extensive northern waters, ranging 
from Greenland to the North Sea, but some of these are evidently doubtful, such as the 
second species of Filograna and several species of Sprrorbis, and there is also doubt concerning 
Vernulia and the two species of Ditrypa and Hydrovdes. 
Claparéde® (1868) includes 10 Serpulids in his Neapolitan Polychets, and they are 
spread over 9 genera, of which Psygmobranchus alone has two species. 
Grube® (1877), records only two species in the extensive collections of the German ship 
“ Gazelle,” viz., a Serpula and a Pomatocerus. In his Philippine Annelids 7 Serpulids are 
entered, six falling under Serpula and one under Ditrypa. 
Levinsen’ (1883) includes 20 species in his northern Polycheets, 7 being Spirorbids, the 
rest distributed over 9 genera, of which Protula and Ditrypa each have two. | 
In the great Expedition of the “ Challenger,” through the diverse waters of the world,® 
22 Serpulids were encountered, the genera most in evidence being Protula (4), Serpula (5), 
and Placostegus (5), the three thus representing more than half the total number secured. 
It is interesting that not a single complete Spirorbis (only two or three fragments of tubes) 
was obtained. In all probability the haunt of the majority of the Spirorbids is the 
littoral region both of foreign seas and our own. 
The Expedition of the U.S. Coast Survey Steamer “ Blake,’’® in the rich waters of the 
Gulf of Mexico and the Caribbean Sea, produced under the able hands of Ehlers (1887) only 
1 “Naturhist. Tids. Kjgbenhayn,’ Bd. i, p. 347. 
> “Cat. Worms Brit. Mus., pp. 264 and 346. 
3 “Annel.,’ t. 11, p. 484, ete. 
* «Annul, Polych.’ (sep. copy), p. 119. 
‘ Annél. Chétop. Naples.’ 
‘Monat. Konig]. Akad. Wiss. Berlin.’ 
‘Meddel. nat. Forh. Copenhagen,’ p. 189, ete. 
‘“ Challenger ” Reports,’ vol. xii. . 
“Results of Dredging, etc.,” ‘Mem. Museum Comp. Zool. Cambridge, U.S.A.,’ vol. xxxi. 
