30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I28 



above, delimited only by the sharp turn of the facial suture at either 

 end. Facial suture in front of palpebral lobe directed strongly inward ; 

 posterior branch starting from the palpebral lobe inward and back- 

 ward, then backward and very slightly outward, finally turning back- 

 ward and inward again before reaching the posterior margin. Posterior 

 marginal furrow deep, terminating in a distal depression, not extend- 

 ing onto free cheeks. Free cheek narrow, with wide, convex border 

 extending into a short, conical genal spine ; marginal furrow weakly 

 impressed only in median portion, setting off the small ocular plat- 

 form rising vertically to the eye. The visual surface has not been 

 observed, and if developed at all it was probably narrow and poorly 

 differentiated. 



Surface of test densely covered with very fine granules. 



Cranidia ranging from i.i to 15 mm. in length supply interesting 

 information on the changes taking place in development. The smallest 

 cranidium (pi. 5, fig. 6) does not show the remarkable specialized 

 features of the adult but is essentially similar to a meraspid cranidium 

 of a generalized ptychopariid. The glabella is parallel-sided and 

 reaches the anterior marginal furrow, the glabellar furrows are fairly 

 well impressed at the sides, and the fixed cheeks lack the peculiar 

 features described above. Cranidia 2 mm. long already show to a 

 considerable degree the characters of the adult, except that the glabella 

 is less tapered and the preglabellar field relatively shorter (sag.). The 

 two last mentioned changes continue to occur even in presumably 

 holaspid cranidia between the lengths of 6 and 15 mm. Note the 

 strongly tapered glabella and great longitudinal extent of the pre- 

 glabellar field in the largest cranidium (pi. 5, fig. 8). 



Occurrence. — The types are from U.S.N.M. locality 48f : Kinzers 

 formation, Smith's Lime Kiln, near York, Pa. The species is common 

 in the boulders of the Ville Guay conglomerate at Ville Guay and the 

 Island of Orleans, and occurs more rarely at Grosses Roches. The 

 illustrated specimens are from boulders O-37, Island of Orleans, and 

 G-24, Grosses Roches. 



Types.— RoXoty^t: U.S.N.M. No. 65002. Paratype: U.S.N.M. 

 No. 65003. Plesiotypes: U.S.N.M. Nos. 123883-4. 



Family SAOIDAE Hupe, 1953 



Genus RIMOUSKIA Resser, 1938 



Description. — Glabella relatively long, very prominent, slightly 

 tapered, well rounded in front. Second to fourth pairs of glabellar 

 furrows deep, straight, transverse, of equal length (tr.) ; occipital 



