TEACHYSYCON.— SIPHONIA. 63 



Teachtsycon sulcatum, Ilinde, u. sp. (Plate XII. figs. 2, 2 «, 2 b.) 



Sponge massive, fig-shaped, widest near the summit, which is depressed or slightly 

 rounded ; the stem has not been preserved. The exterior surface, with the exception 

 of the summit, which appears to have been smooth, is furnished with sinuous, inter- 

 rupted, vertically disposed ridges and furrows, and also with conical, slightly curved, 

 obtusely pointed, spinous processes, about 15 mm. in length, which have no definite 

 arrangement. An average specimen is 110 mm. in height and the same in 

 thickness. 



A wide funnel-shaped cloaca extends nearly to the base of the sponge ; numerous 

 slightly arched canals, 1'5 mm. in width, open into this cloaca ; there are also sinuous 

 branched canals exposed on the summit, radiating from the cloacal margin. The 

 spicular skeleton of the interior is completely obliterated. The surface appears to 

 have been covered with a dermal layer of minute irregular spicules with horizontal 

 sinuously branching head-rays. 



There are two examples of this form in the collection, both of which are com- 

 pletely infilled with silex as well as partially enveloped in it. The species is 

 distinguished from the Trachysycon [PlocoscyiMa) muricatum, Roemer*, by its 

 depressed summit, wide cloaca, and its ridged surface. 



Distribution. Upper Chalk : South of England. 



Genus SIPHONIA (Parkinson), pars, Goldfuss. 



The authorship of this genus is involved in obscurity. The name first appears in 

 the 'Petrefacta Germanise,' p. 16, and is attributed by Goldfuss to Parkinson; but I 

 have been unable to find the term employed anywhere by this last author, though 

 he refers at considerable length in the second volume of his ' Organic Remains ' to 

 sponges of this genus under the general term of Fossil Alcyonia. Most later authors 

 appear to have followed Goldfuss in ascribing the genus to Parkinson without in- 

 dicating where the generic characters were defined. Under these circumstances 

 Goldfuss must be considered the author of the genus, and the first species which he 

 describes, Siphonia piriformis., will have to be regarded as its type. Goldfuss has 

 included in Siphonia the sponges which Lamouroux placed under the genera 

 Hallirhoa and Jerea ; and many later authors, including Prof. Sollas, who has given 

 a very elaborate description of the structure and affinities of Siphonia, adopt the 

 Goldfussian extension of the genus. I purpose, however, to follow the proposal of 

 Prof. Zittel to retain the genus Siphonia for such typical forms as Siplionia piri- 

 formis, tulipa, Jicus, Sec, and to place the lobate forms under the genus Uallirhoa, 

 Lamx., and the forms without a cloacal tube under Jerca, Lamx. It is worthy of 

 notice that if Hallirhoa or Jerea are to be considered as synonymous with Siphonia, 



* Palxontographiea, Bd. 13, p. 28, t. 10. f. 9. 



