CYRTOCERAS APICALE. 33 



Endoceras and Piloceras is too clear to be doubted. Whether their functions 

 were alike is quite another question. Of the functions of the radiating tubuli 

 given off by the endosiphuncle of Actinoceras, which are not present in Endoceras 

 or in Piloceras, the explanation suggested by Owen seems a very rational one, 

 viz. that they served for the passage of blood-vessels to the lining membrane of 

 the air-chambers. They also afforded support to the endosiphuncle, and held it 

 in its central position in the siphuncle. 

 Locality. — Little Island, near Cork. 



Actinogeras PROPINQUUM, sp. nov. Plate IX, figs. 1 a — e. 



This is a fragment of the septate part of a rather slowly tapering species 

 (1 in 7). The septa are deeply concave and wide apart, varying very little in 

 their distance as the shell increases in diameter. The necks are recurved. The 

 siphuncle, which is badly preserved, is composed of somewhat flattened elements 

 (cf. A. in st id are), with the endosiphuncle indistinctly seen as a dark patch running 

 through the centre of the tube, having obscure indications of the characteristic 

 tubuli. The position of the siphuncle is decidedly excentric (figs. 1 c — e). The 

 test is perfectly smooth. 



Remarks. — Though I originally iutended to include the fragmentary form here 

 referred to in Actinoceras insulare, I have since decided that it is better to keep 

 them separate despite their resemblance. This consists in the character of the 

 septa and siphuncle ; in both species the former are relatively wide apart, and in 

 both the elements of the siphuncle are compressed as seen in section (PI. IX, 

 fig. 1 c ; PI. X, fig. 1 d). The complete horizontality of the septa, however, in the 

 present form, and its apparently more slender habit, caused me to hesitate about 

 uniting the two forms without having more satisfactory material than the frag- 

 ment here described provides. 



Locality. — Little Island, near Cork. 



Family C y ktoce uatid^e . 



Cyrtockras (Meloceras) apicai.k, sp. nov. Plate XI, figs. 1 a, 1 b, 2 a, 2 b, 3 ; 



Plate XII. 



? 1851. Ojithockuas unguis, llauf/htcn. Journ. Geol. Soc. Dublin, vol. vi, p. 48, 



pi. — , fig. 3 (not of J. Phillips). 



Description. — Shell of moderate size, rather sharply curved in the lower third 

 of the septate portion, but becoming almost straight above this, so that a frag- 



