62 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 14, 



ception an order perhaps in Anthozoa ; and should a deeply skilled 

 physiologist detect among fossils, e\idences that the functions of the 

 living bodies were performed by peculiar processes, then also it will 

 become possible to establish on a sure basis genera or higher groups, 

 according to the nature of the detected properties. 



Respecting the species of Achilleum enumerated by M. Goldfuss, 

 A. duhium (pi. 1. fig. 2) has been rejected by him (p. 243) ; and 

 additional information is requisite regarding A. glomeratimi (pi. 1. 

 fig. 1) as well as A. Morchella (pi. 29. fig. 6), before their nature 

 can be surmised, although M. Roemer states {op. cit. p. 2), that the 

 latter has a regular trellis-web visible to the unassisted eye : A. fun- 

 giforme (pi. 1 . fig. 3) presents channels and apparently minor pores 

 very analogous to those of common horny sponges, and therefore 

 does not conform to the characters of the genus : A. cariosum (pi. 34. 

 fig. 6) displays (fig. 6 b mag.) a curious resemblance to the corneous 

 recent *S^. cellulosa"^ ; but fig. 6 a shows cylindrical cavities, the 

 round deep piercing holes noticed in the description, and stated to 

 penetrate lengthwise and transversely, and to have occasionally a 

 regular distribution (p. 94). Should those cavities be truly struc- 

 tural, they would indicate great peculiarities m the living body, and 

 remove the fossil from this genus. A. truncatum (pi. 34. fig. 3) in 

 its enlarged representation (3 b) has a composition not very diiferent 

 from that of fig. 6 b, except that the interspaces between the cavities 

 are wider and admit of a more complicated reticulation ; but fig. 3 a 

 is totally destitute of the deep-piercing holes of A. cariosum : it 

 would be difl[icult also to suppose that the minor meshes represent 

 incurrent openings, and the larger apertures excurrent channels, there 

 being no evident relative proportion between the two structures. 

 This species therefore, if rightly understood, approaches more nearly 

 than the preceding to the composition assigned to Achilleum : A, 

 tuberosum (pi. 34. fig. 4) has likewise apparently a simple network. 

 A. cheirotonum (pi. 29. fig. 5), A. muricatum (pi. 31. fig. 3), and 

 A. cancellatmn (pi. 34. fig. 5), have also no visible special apertures, 

 independent of the reticulated meshes ; but the web is peculiar, dif- 

 fering somewhat in each species, though maintaining a general con- 

 formity. It is not very dissimilar from that which Manon marginatum 

 or 3/. impressujn (pi. 34. fig. 9, & fig. 10 5, c) would display, if stript 

 altogether of the dense lamina, and if the preserved surface was be- 

 yond the range of the shallow oscula (pp. 94, 95) ; but there are no 

 data for assummg that any analogous outer structure existed in 

 Goldfuss' s three species of Achilleum. Whether those fossils may 

 be taken as types of the genus must depend on a minute and thorough 

 examination of specimens, full descriptions, and the consent of com- 

 petent authorities. For the present Achilleum must be regarded as 

 a zoological term of doubtful signification. 



One species of the genus, A. costatumf (Miinster), remains to be 



* Ellis and Solander's Zoophj-tes, or Lamouroux's Exp. Method, pi. 54. fig. 1 & 2, 

 nat. size : also Esper's Pflanzenthiere, Sponges, tab. 60. 



t Goldfuss's Petrefacten, p. 94, pi. 34. f. 7, from the middle beds of the Jura- 

 kalk near Streitberg. 



