60 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 14, 



pi. 5. fig. 5, and pi. 30. fig. 1, with pi. 30. fig. 2) ; leaving but five 

 species, and even this small group wants unity of characters* ; also 

 strict conformity with the leading definition of the genus. T. de- 

 forme\ (pi. 5. fig. 3) and T. rugosum (fig. 4), not very dissimilar 

 bodies, and both found in the same formation as wtII as at the same 

 locality (p. 12), exhibit most nearly the required structures, which 

 differ however from those of the Atherfield fossil ; and the other spe- 

 cies are still more unlike that body. 



2. Manoiiy according to Goldfuss, consists of a lacunose fibrous 

 mass, with large circumscribed openings on the surface (p. 2) ; and 

 M. Roemer {pp. cit. p. 2) describes the genus as composed of 

 variously formed masses, consisting of a trellis-like web, or bent and 

 anastomosed fibres, and having on the upper surface round or oval 

 openings with projecting edges. He discards from his characteris- 

 tics an external thick dense layer, concei\dng that the generic separa- 

 tion between Manon and Achilleum should rather depend upon the 

 nature of the network. Of the ten species described by Goldfuss 

 (pp. 2, 94, 220), M. favosum (pi. 1. fig. 11) is removed by himself 

 to Cyathophyllum quadrigemininn (p. 243); M. cribrosum (pi. 1. 

 fig. 10) from the Eifel is possibly a fragment of M. Goldfuss's Astrcea 

 porosa (pi. 21. fig. 7), also from the same district; M. steliatum 

 (pi. 1. fig. 9) is considered by M. de Blainville {pp. cit. p. 543) and 

 M. Milne-Edwards (Lamk. ii. p. 589) as referable to true Alcyonia or 

 Lobulariee, and consequently as not belonging to the class Amorpho- 

 zoa, while ^1. marginatum and M. impressum (pi. 34. fig. 9, 10) 

 are separated from the genus by M. Edwards {pp. cit. p. 588-9) on 

 account of their quadrangular network;];. Of the five remaining 

 species, only M. tubuliferum (pi. 1. fig. 5) and M . pulvinariu?n (pi. 1. 

 fig. 6, Maestricht ; pi. 29. fig. 7, Essen), apparently possess the re- 

 quired generic structures, though under the latter term possibly two 

 species have been included. Distinct circumscribed apertures more- 

 over are not limited to Manon, and they do but characterise certain 

 stages of growth among Amorphozoa generally §. If specimens 

 exhibiting a different condition of development were alone examined, 

 they might be excluded from the genus. Respecting the other three 

 species, M. capitatum (pi. 1. fig. 4) is stated to have a few small 

 openings (p. 2) ; while in the fossils included under the term M. 

 pezizaW and derived from three formations, the apertures present 

 diversities of structure not referable to relative conditions, resembling 



* Consult pi. 5. figs. 3, 4 and 11, pi. 30. fig. 2, also pi. 30. fig. 4. 



•f- Tragos deforme has been accidentally misquoted for T. tuberosum in a notice 

 on the Lymnorea of Lamouroux (Lamk. ii. p. 612 ; Goldfuss, pp. 16, 84 and 243). 



+ Consult also that author's observations on Sp. bombycina, &c. {op. cit. p. 540), 

 and Sp. calyx, \>. 556. Parkinson in his 'Organic Remains,' vol.ii. pi. 7. fig. 8, has 

 delineated certain "cruciform spines," found on the surface of a Swiss fossil 

 (p. 93-95) represented in fig. 9. A comparison with Goldfuss's figures 9 e, 10 c, 

 (pi. 34) almost justifies the inference that the " spines" formed part of a similar 

 network. 



§ Consult figures 8 ^, 8 c, pi. 29. of Goldfuss as illustrative of different condi- 

 tions of fig. 8 a. 



II PI. 1. figs. 7, 8, Maestricht; pi. 5. fig. 1, Essen; pi. 29. fig. 8, Maestricht; 

 pi, 34. fig. 8, Jurakalk of Streitberg, Hattheim, Gingen and Regensburg, p. 94. 



