ON FOSSIL SPONGES FEOM METIS. 



S3 



rods, which may indicate the character of the body of the sponge. (Fig. 24.) These 

 spicules were probably defensive rather than for anchoring. 



(3) Groups of extremely delicate simple straight spicules lying close together and 

 parallel or more or less disturbed. They are narrow, and may have been cylindrical. 

 One group has four long anchoring rods arranged in two pairs. They show no indica- 

 tion of cruciform spicules. (Fig. 25.) 



Fig. 24. — Spinose sponge. Natural size. 



Fig. 25. — Group of spicules enlarged. 



(4) Groups of fine slender spicules either parallel or divergent. Probably root 

 spicules of some species of hexactinellid sponge, and not unlikely Acanthodictya hispida 

 though there is no certainty as to this. 



(5) Large and long solitary spicules, simple and straight, sometimes 0.5 mm. in 

 thickness and several inches in length. They seem quite smooth, but are sometimes 

 flattened at one end. 



(6) Flattened masses of irregularly coalescent fibres like those of lithistid or 

 corneous sponges. They show no anchoring spicules and are irregular in form, and have 

 their structures very imperfectly preserved. 



Nos. 2, 3, 5 and 6 are of rare occurrence in comparison with the other forms. 



Olh:r Orf/an!sms in the Same Beds. 



Obolella (Linnarssonia) pretiosa, Bill. 

 (Fig. 26.) 



Fig. 26. — Linnarmnia pntionci, Billings, a, natural size of inediuui sj[3eciniens, 

 h, ventral, c, dorsal valves. 



In my preliminary note this was compared with 0. Ida of Billings, but according 

 to Prof. Hall, who has kindly examined it, it belongs to the Cambrian genus Lin- 



