276 
SIPHONIOTYPHLUS. 
be continued as a thin selvage. Surface marked with fine 
longitudinal lines. Apertures in alternate, outwardly curved 
series, so that the general diagram of the apertures is pinnate. 
Type Species. 
Siplioniotyjpldm plumatus, Lonsdale, 1850. Dixon, Geol. Suss, 
p. 300, pi. xviii.B, figs. 2, 2a. Chalk : Sussex. 
Affinities. 
Siphoniotyphlus differs from CUnopora by having flattened 
branches on which the apertures are pinnately or sub-pinnately 
arranged. The near afiinity of the two genera is shown by the 
specimen D. 4324, which is in its lower part a typical Siphonio- 
typhlas, but in the upper part this aiTangement is imperfectly 
developed. The genus resembles Porina in the pinnate arrange- 
ment of the apertures and the shape of the zoarium, but Porina, 
though founded as a Cyclostomatous genus, is one of the 
Cheilostomata. 
1. Siphoniotyphlus plumatus, Lonsdale, 1850. 
Synonymy. 
Siphoniotyphlus Lonsdale, 1850. In Dixon, Geol. Suss. p. 300, 
pi. xviii. B, figs. 2, 2a. 
Epidictyon ,, Vine, 1893. Compl. Rep. : Rep. Brit. Assoc. 
1892, p. 336. 
,, tenue, pars, Vine, 1893. Ibid. pp. 323, 336. 
Diagnosis. 
Zoarium of long, thin, unbranched stems, with a shai'p lateral 
selvage. Siu’face ornamented by lines parallel to the series 
of apertures. 
Apertures in curved series of from three to five. The series are 
crowded. 
The distal end of the stem may become narrower, thicker, 
without selvage, and may have irregularly arranged apertures. 
Distkibetiox. 
Upper Chalk : Salisbury ; Sussex. Zone of Bclemnitella mucronata, 
Clarendon. 
Middle Chalk : Chatham. 
