216 ME. JUKES-BROWNE AND PEOF. HAREISON 



should occur a stellate form of crystalloid somewhat similar in 

 appearance to fig. 2 (p. 178), but differing from this in having the 

 bifid extremities of the rays acutely pointed. 



One other mud from "Sirwana, Bantam Coast," bears some re- 

 semblance to the Cole's Cave deposit, in the character of the inorganic 

 material, which, as before, is coarser. Poraminifera, of which 

 Glohigerina is the preponderating form, are more abundant ; but 

 there are several other species, and the aspect of the whole suggests 

 that it is a shallow-water deposit. 



(2) Foraminiferal Limestone. 



Bock Dundo. — Prom 44 feet below the floor of the gully, in a 

 shaft made for the Water Supply Company. This is a semi- 

 crystalline foraminiferal rock, white, but not very hard. When 

 examined under the microscope it appears to combine some of the 

 characters of a chalky Oceanic earth and a granular Globigerina- 

 marl with others which seem to indicate much shallower water. 

 Glohigerince are abundant, but other forms, mobifirng Ampliistegina^ 

 which abounds in the coral-reef rocks, are present. There is, 

 however, an entire absence of the other organic fragments which 

 distinguish coral-reef rocks. 



We consider this to be one of the detrital earths, and the pro- 

 bability is increased by the existence of a green clay which came 

 from the same shaft and which we examined in Barbados ; its 

 organic contents appeared to be chiefly radiolaria encrusted with 

 crystalline growths of quartz or calcite. 



The base of the coral- rock in this shaft is between 38 and 40 

 feet below the gully-floor ; the green clay came from about 40 feet, 

 at 41 feet there was white earth, and the limestone above described 

 at 44 feet. 



(8) Calcareous Earths and Marls. 



From a boring at Lightfoot's ; depth from surface, 130 feet. 

 From Harrison s Cave, 26 feet below the gully-fluor. 

 From a boring at Cane Garden in St. Thomas, depth 110 feet. 

 From a boring in the gully north-east of Pluintree, three 

 specimens from depths of 69, 70, and 80 feet. 



The samples from the first three localities and that from 80 feet 

 down at Plumtree are of a similar nature, being all fine greenish 

 earths consisting mainly of minute calcite-crystals and fine felspatbic 

 material. Calcite predominates at Lightfoot's and at Harrison's Cave, 

 felspathic material in the other two. Miss Raisin remarks that 

 " the calcite is in minute rhombohedra ; rather large angular frag- 

 ments of felspar (up to 4 mm.) occur in two of them, and in one 

 slide (Cane Garden) a few very small chips of brown glass. A black 

 opaque mineral, apparently iron-pyrites, occurs abundantly in 

 scattered s])ots all over the slides, sometimes in perfect cubes, some- 

 times in the form of granules or minate nodular clusters." 



As regards organic remains, Mr. Hill found a few radiolaria in 



