20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I28 



CRASSIFIMBRA, species undetermined No. 2 



Plate 2, figures 9, 10 



Available material. — One well-preserved cranidium. 



Description. — Glabella of low convexity, straight-sided, with fairly- 

 sharp anterior angles ; almost merging with the slope of the preglabel- 

 lar field in front. Occipital ring bearing a node. Preglabellar field 

 greatly reduced medially ; border convex, strongly expanded medi- 

 ally, causing a slight inbend of the marginal furrow. Palpebral area 

 slightly convex, horizontal, half as wide as the glabella ; ocular ridges 

 not greatly elevated. Palpebral lobes half as long as the glabella, nar- 

 row, elevated; distance from posterior end of palpebral lobe to pos- 

 terior margin somewhat less than length of palpebral lobe. Posterior 

 limbs as wide (tr.) as occipital ring, well rounded distally ; distal por- 

 tion somewhat narrower (tr.) than proximal portion. Anterior facial 

 sutures slightly convergent from eyes to marginal furrow ; posterior 

 branch directed straight outward behind eye. Surface of test finely 

 granulated. Length of cranidium 6 mm. 



Remarks. — This distinctive species does not exactly fit the char- 

 acters of any described genus. It seems best placed in Crassifimbra 

 on account of the narrowness of the palpebral area. It differs from 

 Crassifimbra walcotti in the depth of the dorsal and marginal furrows, 

 horizontal palpebral area, prominence of the anterior border, long 

 palpebral lobes, and granulated surface. 



Occurrence. — Boulder B-i, Bic ; associated with Bonnia laevigata 

 Rasetti, Protypus sp., Zacanthopsis sp. 



Disposition of material. — U.S.N.M. No. 123875. 



LUXELLA Rasetti, new genus 



Description. — Glabella straight-sided, tapered, not greatly elevated, 

 well defined by the dorsal furrow at the sides, truncated and poorly 

 delimited in front, occupying half the cranidial length. Preglabellar 

 field long (sag.), slightly downsloping ; border wide (sag.), slightly 

 convex. Palpebral area flat, horizontal, as wide as the glabella ; ocular 

 ridges visible ; palpebral lobes elevated, almost half the glabellar 

 length, at the level of the glabellar midpoint. Posterior limbs some- 

 what wider (tr.) than the occipital ring, well furrowed, with distal 

 part bent downward. Anterior facial sutures divergent in front of the 

 eyes for a considerable distance, curving inward in crossing the bor- 

 der ; frontal portion slightly ventral. Posterior branch directed first 

 straight outward, then curving backward to posterior margin. 



Type species. — Ptychoparia lux Walcott. 



