68 THE NAUTILUS. 



Type No. 9316 Collection of the Wagner Free Institute of Science. 

 Tliis species belongs to the typical cereolus section, but has the size 

 and form of P. iivulifera. Dr. Dall records P. cereolus microdonta 

 from the Caloosahatchie beds (Trans. Wagner Free Inst. iii, pt. 1, 

 p. 19), but this species cannot be confounded with that. 



VIVIPAROUS MIOCENE TURRITELLIDJE. 



BY FRANK BURNS. 



I have lately made one of the most interesting discoveries that I 

 have met with in all my work in the Southern Tertiary, and send 

 you below the facts for publication. 



I lately went to -Plum Point, a classical spot in Maryland, to try 

 to get a fair representation of the fauna there, as the beds and shells 

 are so friable that it has been heretofore almost impossible to do so. 

 I have a large amount of marl and many hundreds of the larger bi- 

 valves, collected to get the small things enclosed in the matrix be- 

 tween the valves, also in such gastropods as I could get out without 

 breaking. In looking over some sand I came across a small frag- 

 ment of Turritella cumberlandia Con., 21 mm. long and 11 mm. 

 wide, and out of this I obtained over two hundred embryonic shells 

 that were enclosed in the mother shell. Of all the great number of 

 thousands of such shells that I have heretofore collected, I never saw 

 anything like this, nor have I read of it. 



These embryonic shells were never born, so to speak. Their 

 mother died with them enclosed, and, as the animal decayed, the 

 front of the aperture was closed with fine silt, leaving the embryonic 

 shells intact, where they have remained for an immense period of 

 time, as this is the lowest fossiliferous bed in the Miocene. These 

 embryonic shells are about one millimetre in length and about as 

 wide. I have heretofore collected very young Turritellida from fine 

 sand where they had died, but never before saw one in the parent 

 fossil. A fine point for investigation is whether the recent Tarri- 

 teUidce are oviparous or viviparous. The literature that I have 

 access to is a little hazy on the subject. 



Since writing the above I have found another specimen in the 

 same condition, but of a different species, Turritella indmta Con.; 

 both from the same bed at Plum Point. 



