190 Mr Lister, The Skeleton of Astrosclera etc. 



from the Carboniferous to the Cretaceous period. A difference 

 however exists in the character of the elements of which the 

 skeleton is composed. In Astrosclera these are polyhedral masses, 

 having a radial arrangement of the crystals of aragonite which 

 compose them, while in the best preserved specimens of the 

 Pharetrones the skeleton is composed of more or less modified 

 three- or four-radiate spicules, presumably of calcite. 



The case was considered of the representatives of the Phare- 

 tronids occurring in Triassic strata near St Cassian in the Tyrol, 

 in which the skeleton often has a radiating structure, in many 

 cases closely resembling that found in Astrosclera. The view 

 generally held by Palaeontologists is that the radiating structure 

 of the St Cassian forms is secondary, and due to a recrystallization 

 in the fossil state, which has obliterated the original elements of 

 the skeleton. This conclusion was held to be correct, notwith- 

 standing the marked resemblance of the resulting structure with 

 that of the skeletal elements of Astrosclera. 



While their similarity in this respect was rejected as evidence 

 of affinity, it was pointed out that the resemblance between the 

 skeletal elements formed within the living protoplasm of Astro- 

 sclera and the bodies formed by purely physical processes in the 

 St Cassian fossils may have a bearing on the problem of the mode 

 of origin of sponge spicules. 



Note on the name Balanoglossus. By S. F. Harmer, Sc.D., 

 King's College. 



[Received 15 November 1899.] 



The generic name Balanoglossus (Delle Chiaje, 1829) has been 

 shown by Carus and Spengel 1 to be synonymous with Ptychodera 

 (Eschscholtz, 1825); and Spengel has accordingly accepted the 

 earlier name, retaining Balanoglossus, however, in a restricted 

 sense. The species found by Eschscholtz in the N. Pacific was 

 named by him Ft. flava; while Delle Chiaje's species was the 

 well-known Mediterranean Balanoglossus clavigerus. Both these 

 species are referred by Spengel, throughout the greater part of his 

 Monograph, to the genus Ptychodera, although on p. 359 he 

 suggests a provisional breaking up of this genus into three ; 

 Ptychodera (s. str.), Tauroglossus, and Chlamydothorax. B. clavi- 

 gerus is placed in Tauroglossus, in which Pt. flava is also doubtfully 



1 Spengel, J. W., "Die Enteropneusten des Golfes von Neapel," Fauna u. 

 Flora G. von Neapel, 18 Monogr., 1893, pp. 12, 349. 



