Chap. IX.] 
LOWER SILURIAN ZOOPHYTES. 
189 
sites catenularius of Linnseus, Foss. 31. f. 4, the well-known 1 Chain-coral ' 
(Catenipora escharoides of the ' Silurian System '). Another, still more abun- 
dant in the lower rocks, is Favosites fibrosus, both branched, f. 1, and hemi- 
spherical, f. 2. Petraia subduplicata, f. 3, is but rarely found below the horizon 
of the Llandovery rocks ; P. rugosa, Phill., and P. sequisulcata, M'Coy, are, 
however, not unfrequent Caradoc species. 
Others, less common, are Stromatopora striatella (doubtfully grouped with 
Corals), Chap. X. Foss. 52 ; Heliolites interstinctus, p. 120, Foss. 19 ; H. inor- 
Fossils (31). Lower Silurian Zoophytes and Polyzoa. 
1. Alveolites (Stenopora, Sil. Syst.) 
fibrosus, Groldfuss. 
2. The same species, variety Lyco- 
perdon, Hall. 
3. Petraia subduplicata,!!' Coy ; rarely 
found in the Caradoc strata. 
4. Halysites catenularius, Linne. 
5. Ptilodictya dichotoma, Portlock. 
6. Retepora Hisingeri, M'Coy; Ca- 
radoc rocks of Westmoreland. 
dinatus, Foss. 30. f. 5 ; H. megastoma, f. 7. Both these last are plentiful at 
Eobeston Wathen in Pembrokeshire. Heliolites petaliformis, p. 120, Foss. 19. 
f. 2, and H. tubulatus, ib. f. 1, have also been quoted by M'Coy from the Caradoc 
rocks of Westmoreland : H. favosus of the same author is a rare Lower Silurian 
species from Ayrshire. We have also Favosites Gotlandicus, Foss. 30. f. 6 ; 
F. alveolaris, p. 119, Foss. 18. f. 4 ; and the Sarcinula (or Syringophyllum) 
organum, Linn., Foss. 30. f. 4, found in the slates of Westmoreland and in the 
Upper Silurian limestone of Gothland in Sweden. Nebulipora of Professor 
M'Coy contains one or two species of minute-celled Corals, resembling Favo- 
sites, and is chiefly Lower Silurian. One, Nebulipora favulosa of Phillips, 
figured in the woodcut, p. 51, Foss. 11. f. 22, is very common in the Llandeilo 
flags; both it and Monticulipora (Nebulipora) lens, M'Coy, are very charac- 
teristic Caradoc fossils, p. 68 : M. papillate, M'Coy, is both a Lower and an 
Upper Silurian species. 
The reader has before him in these woodcuts a few only of the Corals 
which most frequently occur in Lower Silurian strata ; but if he wishes 
to study many other forms of these fossils, particularly those in the Upper 
Silurian rocks, where Corals are much more abundant, he must consult the 
clear and faithful descriptions of them given by Mr. Lonsdale in the 
' Silurian System,' in which work 62 species are accurately figured *. By 
reference to the authority of that valued friend, who assisted me so mate- 
rially in preparing my original volumes, and to the works cited in the foot- 
note, it will be seen that, of the seventeen or eighteen species here mentioned 
as found in the Lower Silurian, no less than eight, including the Chain- 
coral (Halysites catenularius), Favosites alveolaris, F. Gotlandicus, and the 
* The palaeontologist will also naturally consult graphical Society, 1854. I must also specially re- 
the writings of Milne-Edwards and Jules Haime, fer the naturalist to Dana's magnificent work on 
Archives <fu Muse'um d'Histoire ISTaturelle, vol. v., Zoophytes, published as part of the results 
who have shown that several of the Corals which of the United States Exploring Expedition ; 
were supposed to be common to the Silurian and and to Prof. M'Coy's descriptions and figures 
Devonian systems are not identical. See their in Professor Sedgwick's work, Descript. Brit. Pal. 
Monograph in the publications of the Palasonto- Foss. of the Woodwardian Museum. 
