xliv DESCRIPTIVE REMARKS. 
the conclusion as to the near relation of the genus to the recent 
Delphinula. Of the more elevated spiral shells, Murchisonia balteata, 
fig. 10, is acommon Wenlock form; Acroculia prototypa, fig. 11, and 
A. haliotis, fig. 12, are very abundant in the Wenlock limestone, parti- 
culary the latter species. 
Of the Hererovopa, Bellerophon dilatatus, Tl. xxii., fig. 1 a, is one 
of the largest examples, commencing in Caradoc strata, and continuing 
into the Llandovery and Wenlock rocks. B. Wenlockensis, fig. 2, is 
another large species, very characteristic of Wenlock strata, as implied 
by its name. 
Of Prerorop Suetts but few species are known in Upper Silurian 
strata, besides Zheca anceps, fig. 3, and 7. Forbesiz, Pl. xxvi., fig. 6, 
before mentioned as Wenlock shale species; Conularia Sowerbyi, fig. 5, 
is often found in Wenlock limestone, and occurs, with a rarer species, C. 
subtilis, in the Ludlow rocks of Westmoreland. 
Of the CrepHatopopa as many as fifteen species are enumerated as 
occurring in the Wenlock series, Orthoceras annulatum, fig. 4, previously 
cited, and its variety, fimbriatum, although commencing in Caradoc 
strata, and continuing into the Llandovery, 1s most char acteristic of the 
Wenlock limestone. ‘There are many other species, some of them also 
ranging from Caradoc strata, through the whole of the Upper Silurian 
series, such as O. filosum, O. ibex, and O. subundulatum. The genera 
Phragmoceras and Lituites are represented by a few and nearly equal 
number of species. 
The Cirrhipedia, now classed with the Crustacea—a group which 
includes the barnacles or acorn shells—had its earliest representative in 
the Wenlock limestone, in a pedunculated form, resembling Loricula, 
named Turrilepis Wrightianus, and described by Mr. Henry Woodward 
from the limestone of Dudley. 
Tritosires* of certain species are very abundant, especially Calymene 
Blumenbachii, Pl. xxiii., fig. 1; a species ranging from Caradoe to Lud-. 
low strata, Hncrinurus punctatus, fig. 2, and LH. variolaris, fig. 3, are 
very common both in the limestone and shale; Phacops caudatus, fig. 5, 
ranging from Llandovery to Ludlow, is most frequent in the Wenlock 
rocks. JP. Downingie, fig. 6, having the same stratigraphical range, 
is one of the most characteristic Trilobites. Proetus latifrons, fig. 8, 
with another species, P. Stokesiz, are not uncommon in Wenlock 
strata; lenus Barriensis, fig. 4, ranging from Llandovery to Wenlock 
strata, most frequent in the latter; and Homalonotus delphinocephalus, 
fig. 7, before cited, as also occurring in the lower Wenlock or Wool- 
hope limestone. The small bivalve crustaceans (belonging to the Phyl- 
* Since writing the remarks on page xiii, relative to parts of a Trilobite, the dis- 
covery of a series of eight pairs of jointed legs attached to an equal number of thoracic 
segmentsin a Trilobite (Asaphus platycephalus) found in Canada, was announced to the 
Geological Society of London, May 17th, 1870, by Mr. E. Billings, Palontologist to 
the Geological Survey of Canada. Other organs, believed to be the palpus of one of the 
maxille, were recognised by Mr. H. Woodward, in additional specimens of Trilobites 
from Canada, exhibited at the same meeting. 
