1 58 NEW YORK STATE MUSEUM 



and clean casts of the borings; or when these natural conditions 

 are reproduced artificially by removing the calcareous material 

 from a lime shale. 



Probably the first attempt to characterize with a definite name 

 these undoubted sponge borings was that of McCoy [Brit. Paleoz. 

 Foss. 1855. p. 260, pi. iB, fig. I, I a] who illustrated under the name 

 Vioa prisca a series of simple straight club-shaped casts of 

 borings occurring in the shell substance of the pelecypod identified 

 as Pterineademissa Conrad of the Upper Siluric. It is 

 probably safer not to designate these sponge relics by the name of 

 any genus now living and I propose, in speaking of several distinct 

 forms of them, to employ the term Clionolithes. 



The straight claA^ate tubes of Clionolithes priscus 

 (McCoy) usually originate at the edge of a dead shell and expand 

 gently inward ; probably the sponge nested at the club-shaped ex- 

 tremity of the hole, drawing the water currents in to itself. It is 

 not always the case that the shell was dead before the work 

 of these borers began. .There are several illustrations given here 

 to show that a braehiopod or pelecypod may have been attacked 

 by these sponges at any growth stage and that after the attack had 

 begun the growth of the shell continued. There is a curious 

 simultaneousness in the attacks of these pseudoparasites — all 

 .started in at once and frequently one such attack is not followed 

 by others [see pi. 8, fig. 2, 4]. This form, C. priscus, was quite 

 common in the late Siluric and very abundant throughout the 

 Devonic. 



Clionolithes radicans designates a quite different 

 expression of this boring habit. Here the tubes radiate and branch 

 outward from a center, giving a decided rootlike expression to the 

 resultant very complicated combination of tubes. These branch- 

 ing tubes often unite, fuse or anastomose producing a somewhat 

 irregularly reticulated expression. This sponge particularly in- 

 fested the living and dead shells of the brachiopods, finding en- 

 trance less often at the margin than through the pores on the 

 surface of the shell. The complex of tubules is small in comparison 

 with those of C. priscus and it is not unusual to find both of 

 these forms infesting the same shell. This boring sponge, so far as 

 my observation extends, is restricted to the Devonic. 



Clionolithes reptans has threadlike vermiform tubes 

 which wander loosely and at random through the shell substance 

 of both brachiopods and pelecypods. 



