166 
G. W. Lee — Trepostomata. 
this form is to be regarded as an offshoot from the common Tabulipora scotica or as a 
mutation of Tabulipora hoivsei (Nich.). 
Furthermore, materials, unfortunately insufficient for close study, show that a genus- 
possessing mesopores is also present in the Lower Limestones of the East Kilbride district. 
Assuming that the specific distinctions made here are justified, it follows that at least five- 
species of Trepostomatous Bryozoa occur in the East Kilbride region. And, since Ure’s 
“ Millepore ” came from that district, Young’s view that any specimen could be regarded 
as a topotype cannot be upheld, nor can his proposal to revive its first Linnean name,. 
Cellepora urei Flem., be adopted, 1 the original of lire’s “ Millepore” being lost. 
Regarding the mutual relationships of the three species Tabulipora scotica , T. youngi 
and T. minima , little can be said, since they are all from the same horizon and their pro¬ 
genitors in lower deposits cannot be traced. However, as they qccur in the same 
sediments, it does not seem probable that they represent different conditions of the 
same organism. T. scotica evinces a tendency to the loss of moniliform structure, but 
the total loss of this feature would not suffice to evolve an organism undistinguishable 
from T. youngi , in which the peripheral portion of the walls is thicker and longer. 
T. minima has been compared with equal-sized specimens of the two other species, and its 
distinguishing characters have been found to hold good ; it cannot, therefore, represent 
small branches of either. 
Tabulipora howsei (Nicholson). 
Plates XIY, figs. 9 A-9 C ; XY, figs. 22-24. 
1881. Stenopora Howsii Nicholson. On the Structure and Affinities of the Genus- 
Monticulipora and its Subgenera, pp. 82, 83. 
1883. Stenopora Hoivsii Nicholson. Contributions to Micro-Palaeontology. On 
Stenopora Howsii , Nich., with Notes on Monticulipora ? tumida , Phill., and 
Remarks on Tabulipora Urii, Young. Ann. Mag. Nat. Hist., vol. xii., Fifth 
Series, p. 285, pi. x. 
Description. —(a.) External characters. The zoarium consists of hollow or solid 
branches, cylindrical or oval in section, from 5 to 20 mm. in diameter. Complete colonies 
have not come under observation, but the thickest yet seen very likely exceeded 20 cm. 
in length. The branching is dichotomous alternate. The hollow and solid modes of 
50, p. 154. 
