27 



MONTICULIPORA PARASITICA MULTIPORA, Var. UOV. 



Plate IV, Figure 2; Plate VI, Figure 8 



Monticulipora parasitica, Ulrich. Jour. Cincinnati Soc. Nat. Hist., 5, 1882, p. 238, pi. 10, 



figs. 3, 3a. 

 Monticulipora parasitica, /. F. James. Ibid., 18, 1895, p. 81. 

 Monticulipora parasitica, Cumings. 32nd Rep. Dept. Geol. Nat. Res. Indiana, 1908, 



p. 862, pi. 21, figs. 2, 2b; pi. 31, fig. 2. 



The original description of Monticulipora parasitica, somewhat abbreviated, 

 is as follows: — 



The zoarium is usually attached to Streptelasma (corniculum). Regularly arranged in 

 decussating series and at distances apart of about .1 inch, the surface presents small conical 

 monticules, the summits of which usually appear to be solid, as they are occupied by minute 

 cells; while on their slopes they carry the apertures of cells slightly larger than the average. 

 The largest of these have a diameter of 1/85 of an inch (about seven to two millimetres). The 

 spaces between the monticules are flat and are occupied by the polygonal and moderately thin- 

 walled ordinary cells varying from 1/110 to 1/100 of an inch (eight to nine in two millimetres). 

 Interstitial cells (mesopores) are developed only in the monticules, the summits of which are 

 usually occupied by their apertures. 



Tangential sections show the tubes to be polygonal. Their angles of junction are usually 

 thickened and the small space thus formed incloses almost invariably a minute lucid spot. They 

 represent in all probability very small spiniform tubuli (acanthopores). Between the groups of 

 slightly larger cells a few thick-walled minute tubes (mesopores) may generally be observed. 



Longitudinal sections show that all the matured tubes have one or both sides lined by a 

 series of cystoid diaphragms while the space between the double series and opposite wall is 

 crossed by straight diaphragms, which are placed at distances apart of about one-third of a tube- 

 diameter. (Diaphragms only are found in the mesopores.) 



Cumings (op. cit.) makes the following remarks concerning a form which 

 he finds at the base of the Liberty at Weisburg, Indiana, and which he refers to 



Monticulipora parasitica : — 



The specimen figured by me may not belong to this species as it has well developed meso- 

 pores. Its habit and superficial appearance are, however, the same as those of Ulrich's species. 

 In its internal characters it is more like M. cincinnatiensis , James. 



Two specimens were obtained from the Streetsville member which appear 

 to belong to Monticulipora parasitica except for the fact that they possess 

 numerous mesopores. In this respect they agree with the form described and 

 figured by Cumings from the Liberty of Indiana, as belonging to this species. 

 The apparent identity of our specimens with those of Cumings and the constant 

 departure from the type of the species, as indicated by the presence of mesopores, 

 seems to justify the creation of a new variety. The new variety resembles 

 M. cincinnatiensis, as stated by Cumings, but it differs in having acanthopores 

 and in the lower type of monticule. 



Locality. — Credit river, Streetsville. 



Nos. 12168, 12169, Royal Ontario Museum of Paleontology. 



Stigmatella hybrida, sp. nov. 

 Plate IV, Figures 7 and 8; Plate VII, Figure 1 



A bryozoan, which differs from any previously described species, was 

 found in the Strophomena varsensis zone of the Streetsville member at Cooksville 

 creek. The zoarium consists of a large, more or less cone-shaped mass, measuring 

 40-45 mm. in diameter, with a smooth surface, there being no evidence of either 

 maculae or monticules. 



In tangential sections, the typical appearance of S. crenulata, Ulrich and 

 Bassler, is presented. Zooecial tubes are of medium size. The acanthopores, 



