30 DE. J. W. OEEGOEY ON THE GEOLOGY AND [Feb. I9OO, 



Mr. Parkinson l from the sides of the Miriya Pass, above Dongorreh, 

 in the ranges of Artalla and Bnr Dab, and as far south as God-la- 

 Yareh. 



Hence it is clear that the marine limestones are widely distri- 

 buted in Somaliland on the summit of the plateau. As some 

 limestones of the same age also occur in the low-lying Guban at the 

 foot of the plateau-scarp, the formation of the Aden depression was 

 later than the deposition of the high-level limestones, for the age of 

 which we must turn to the palseontological evidence. 



IY. The Fossil Coeals oe Somaliland. 



Description of the Species. 

 Genus Stylophoea, Schweigger, 1820. 



1. Stylophoea tistillata (Esper). 



1797. Madrepora pistlllata, Esper, ' Pflanzenth.' Fortsetz. vol. i, p. 73, Madvep. 

 pi. lx. 



1820. Stylophora pistillaris, Schweigger, ' Handb. Naturg.' p. 414; 1879. St. pis- 

 tillata, Klunzinger, ' Korallth. roth. Meer.' pt. ii, p. 62. 



Distribution. — liaised Reefs, Guban near Berbera. Coll. 

 Capt. E. T. Marshall. 



2. Stylophoea palmata (de Blainville). 



1830. Sideropora palmata, de Blainville, Zooph. in Diet. Sci. Nat. vol. lx, p. 350. 

 1857. ^SV///o^//o;v'7^(//^r(/Y(,Miine-Ed\vards&Haiine; 'Hist. Nat. Cor.' vol. ii, p. 137; 

 1879. Klunzinger, k Korallth. roth. Meer.' pt. ii, p. 63., 



Distribution. — Kaised Beefs : Guban, near Berbera. Coll. 

 Capt. E. T. Marshall. This ' species,' which may be only a form of 

 St. pistlllata with more compressed branches, is represented by a 

 small specimen. 



3. Stylophoea eeondosa, sp. nov. (PI. I, figs, la-lc.) 



Diagnosis. — Corallum large and caespitose; with thick, strongly 

 compressed, twisted branches. Corallites small, about 1 mm. in 

 diameter, very crowded ; the calices are deep and the lower margins 

 raised. Columella prominent. 



Septa in one cycle ; all six septa equal in size and united to the 

 columella. Endotheca in distant, tabuliform lamellae. 



Distribution. — Duban : low-level alkali plain, north of the foot 

 of the Bugga Pass. Coll. Mrs. Lort Phillips. 



Affinities. — This coral occurs as a series of branches ramifying 

 through a large block of limestone. In many places the coral has 

 been removed, leaving the interspaces as confluent sheets of lime- 

 stone ornamented by minute granulations or tubercles which are the 

 casts of the calices. These bands of limestone stand out as branched 

 expanded sheets, resembling in appearance a crateriform sponge. 

 The branches of the coral occur as depressions between the raised 

 limestone-bands ; and it was only by breaking away the latter that 



1 F. B. Parkinson, ' Two recent Journeys in Northern Somaliland ' Geogr. 

 Journ. vol. xi (189S) pp. 17, 19, 25 & 28. 



