!24 ANNALS NEW YORE ACADEMY OF SCIENCES 



increasing its diameter. Neither the initial point nor the true aperture ap- 

 pears to be shown. The cross-section must have been nearly circular. The 

 shell substance, when preserved, is lamellose. phosphatic, of a light bluish 

 color and in places distinctly nacreous. For the most part, however, the shell 

 appears to be missing and only the muddy infilling of the tube remains, of a 

 rusty color and partly with a dark limonitic coating. Where the entire organ- 

 ism is removed, its place is represented by a groove. As the original test of 

 the Orthoceras is now absent, this impression naturally occurs on the mold 

 of the inside and the explanation of the phenomenon is difficult. I think we 

 can not assume that the organism was originally attached to the inside of the 

 Orthoceras, because of the septa. It may, however, have been attached to the 

 outside or have been partly imbedded in the shell, through the gradual solu- 

 tion of which these external bodies, insoluble under prevailing conditions, 

 were brought into contact with the mud which filled the interior. This 

 hypothesis, however, is unsatisfactory, because the specimen is not bent but 

 broken by the compression which it has suffered, showing a rigid condition 

 at the time the force was applied. 



The shape and phosphatic appearance of this organism are characteristic of 

 Enclwstoma, but such Enchostomas as I have heretofore seen are free and of 

 larger size. The small size, sessile condition, and probably false appearance 

 of having been partly imbedded in the shell of its host, are very suggestive of 

 the organism which I have here called Serpulopsis insita, but none of the 

 specimens of Serpulopsis shows any evidence of having had a phosphatic shell. 

 They are also small and very much shorter. The true relationship of this 

 form and its position in the animal kingdom remain problems as yet unsolved. 



Horizon and locality: Wewoka formation; Wewoka quadrangle, Okla. 



Serpulopsis gen. nov. 



This name is introduced for some small tubular organisms which enlarge 

 very gradually and are frequently much contorted during part of their growth. 

 They have the habit of attachment to other organisms and are more or less 

 imbedded in the shell of their host. They always keep near the surface, but 

 are perhaps as seldom completely superficial as they are completely imbedded. 



I can scarcely doubt that the fossils on which this genus is founded 

 belong to White's Serpula insita, which, consequently, is taken as the 

 type. 



Serpulopsis is distinguished from Serpula by its burrowing habit, 

 which is in fact abnormal for the annelids. Even if the excavations 

 alone and not the tubes which ordinarily occupy them were known, it 

 would be impossible to refer these structures to the boring sponges which 

 they somewhat suggest, because of their strictly superficial, linear and 

 not inosculating character. In some respects, they suggest Rhopalonaria 

 among the Bryozoa, but, while specimens frequently occur together in 

 considerable numbers, they appear to form groups of independent indi- 



