ADDENDA. 
23 
flexuous, conical, in section cylindrical, or somewhat flattened laterally, and sub- 
triangular. Walls of the tube thick, cellular along the surface opposite to the 
attached portion, markedly annulated along the sides. 
“ Ortonia conica, Nich.—Tubes growing attached to the shell of some Mollusc; 
varying in length from a quarter to half an inch, with a diameter of about one- 
tenth of an inch at the mouth. Lateral annulations of the tube varying in 
number from thirty to thirty-five in the space of an inch. Surface smooth and 
completely destitute, so far as observed, of longitudinal strim. 
“ The fossil from which the above description has been taken is an example 
of Strophomena altermta, to the dorsal valve of which are attached the remains 
of more than twenty individuals of Ortonia conica. In one case the tube of one 
crosses that of another individual; but it is quite clear that this is an accidental 
circumstance, so to speak, and that the tubes are truly solitary. The specimen 
is from the ‘ Cincinnati group ’ of South-western Ohio, a formation which be¬ 
longs to the ‘ Hudson River series,’ and which corresponds with the Caradoc or 
Bala division of the Lower Silurian. 
“ In conclusion, I may add that Mr. Orton has submitted to me a beautiful 
specimen, apparently of the Tentaculites tenuistriata of Messrs. Meek and Wor- 
then, and also from the Cincinnati group of South-western Ohio. If this 
specimen be rightly determined, I cannot avoid the conclusion that it is truly 
referable to the genus CornuUtes of Schlotheim, differing from the familiar Cor- 
nulites serpularius in its small size, and in some other minor characters. This 
conclusion, however, does not admit of complete verification except by the dis¬ 
covery of specimens absolutely attached to some foreign body.” 
In the Geological Magazine, vol. x, 1873, the same author publishes “Descrip¬ 
tions OF Two New Species of Fossil Tubicolar Annelides.” He redescribes 
the genus Conchicolites and the species C. gregarius, and describes the follow¬ 
ing new species— Conchicolites corrugatus, Nich., and Ortonia minor —in the 
following terms: 
“ Conchicolites corrugatus, Nich.—Tubes growing socially in clustered masses 
upon the shells of molluscs; calcareous; destitute of vesicular structure ; coni¬ 
cal, and gently curved. Attached by their smaller extremities, sometimes for 
the space of a line or more; and either partially free, or contiguous to one 
another throughout the remainder of their course. Length of the fully-grown 
tube one-half inch or a little more; diameter of tube at mouth one- tenth of 
