W. H. Ball— Geology of Florida. 163 



effect that between Tampa and the Keys, coquina-rock is only 

 to be found at one place, the mouth of Little Sarasota Pass. 

 But this idea is. certainly erroneous, as at every projecting 

 point of the Keys along the Gulf shore which we visited, I 

 found traces of this rock, though often not visible above water, 

 and frequently composed more of sand-grains than of shell, so 

 that it looks much like wet loaf sugar. It is doubtless being 

 formed at many points along the Gulf shore, though in small 

 quantities at each place, and not at all in the lagoons and har- 

 bors. 



Another species of rock which strikes a northern observer as 

 curious, is in process of formation by immense compact colonies 

 of Vermetus nigricans, which raise the orifices of their minute 

 blackish tubes to several inches above low water mark, and in 

 some of the larger bays have formed extensive reefs. The 

 animal has been supposed to be a worm, belonging among the 

 Serpulce, but I was able to determine its proper place by an 

 examination of the soft parts. I have seen none of this rock 

 in a strictly fossil state, though the species seems to occur in 

 the Caloosahatchie Pliocene, but it is locally known as "worm- 

 rock " and many of the " rocks " described by the natives of 

 this region as cropping out along the shores, turn out on more 

 particular enquiry to be of this kind. 



There are three other sorts of rock of which the formation 

 appears to be still going on. One is a more or less indurated 

 sand, which was observed at Myers ; also near St. James City 

 on Pine Key ; about a mile from the shore of Little Sarasota 

 Bay, on South Creek, where it was found in the banks under 

 the usual layer of sand ; and close to the landing wharf at Sara- 

 sota, on Big Sarasota Bay. This rock is usually rather soft 

 and contains recent land and a few recent marine shells. In 

 other places, as at St. James City, it becomes extremely hard 

 and compact, ringing under the hammer and almost destitute 

 of fossils. A thin layer of it, from a mere film to three inches 

 thick, marks the upper surface of the much older outcrop at 

 White Beach, Little Sarasota Bay. 



A second variety of rock is formed by springs containing 

 iron in solution, which are numerous along the main shore as 

 in both Sarasota Bays. This water consolidates the gravel, sand, 

 shells, etc., over which it passes, into something resembling 

 coquina, but in which the fragments of shell, etc., are united 

 together by a. cement of limonite. A spring near the estate 

 of Judge Webb at Osprey, has thus affected a considerable 

 part of what appears to be an Indian shell-heap ; and among 

 the shells, etc., in the rock may be detected fragments of pot- 

 tery. Specimens showing this were brought home, and it is 

 probable that the human remains discovered by Professor Heil- 



