MARINE INFUSORIA. 



fabricators and inhabitants of these elegant helmet-shaped tests are not 

 Radiolaria, but belong to the more highly organised group of the Ciliate 

 Infusoria, representing among the same a specially modilied form of the 

 Vorticellida) and other familiar members of the section Peritricha. The 

 test itself, except for its sUicious consistence and cancellated structure, 

 corresponds morphologically and physiologically with the horny or 

 chitinous protective lorica of a C'othurnia or Vafjinicola. It is a secretion 

 or exudation of the external cuticula. The enclosed animalcule, how- 

 ever, as shown by Hasckel, exhibits a very wide divergence from the 

 ordinary Peritrichous type. The body of the same is attached posteriorly 

 to the proximal or hinder extremity of the cavity of the lorica, while the 

 more expanded oral or distal region is projected, when the animalcule 

 is extended, beyond its everted anterior margin so far that the tout 

 ensemble may be compared to a minute bell, in which case the lorica 

 represents the bell-body, and the posteriorly attached animalcule the 

 clapper. It is in the projecting oral region of the animalcule that the 

 essential points of modification are found to obtain. Here, in place of 

 the customary simply circular or spiral wreath of ciha, the margins of 

 the oral disc are produced into about twenty long tentacle-like organs, 

 probably of a prehensile nature, which, as the animalcule swims 

 mouth downwards thx'ough the water, impart to it the aspect of a 

 minute jelly fish or medusa. Inside the outer wreath of tentacles, 

 which would appear to represent outgrowths or prolongations of the 

 raised peristome-border of an ordinary Vorticella, is situated an inner 

 circlet of stout vibratile ciha, which conducts to the oral aperture. This 

 is apparently homologous with the adoral ciliary wreath of the same 

 peritrichous type. Dictyocysta cassis, with which the minute siUcious 

 lorica taken in the towing-net on the Cornish coast entirely corresponds, 

 was originally discovered by Professor Hasckel, in the neighbourhood of 

 Messina, and its recent encounter in so much more nox-therly a latitude 

 is of itself a feature of considerable interest. Thi-ee other species of 

 Dictyocysta, aU distinguished by various modifications of the form of the 

 lorica, or in the pattern of its perforations, were obtained by Professor 

 Haeckel from the same Mediterranean station, which would appear 

 to he within its most congenial and favoured area of geographical distri- 

 bution. Two remaining species, upon which, in the year 1854, the genus 

 was first founded by Ehrenberg, were encountered in deep Atlantic sound- 

 ings, and no doubt originally lived, like Noctiluca and the Radiolaria, in the 

 surface waters. Three infusorial tj^pes, having tentacle-like appendages, 

 similar to those of Dictyocysta, but with loricse formed of chitine, with 

 an admixture of agglutinated sand gx-ains and other foreign particles, 

 have been described by Professor Haeckel. in the serial above quoted, in 

 association with the new generic title of Codonella. The deUneation here 

 given of the animalcule of Dictyocysta cassis is reproduced from 

 Haeckel's illustrations, that of the lorica being a sketch from the 

 Falmouth specimen. 



2. — Tintinims subulatus, Miiller, (Plate IV., Fig. 3.) — A single 

 example this type has been found mixed with the preserved diatoma- 



