848 ORDER TENTACULIFERA-ACTINARIA. 



action, to engulph the divided fragments at separate regions of its body. The 

 extrusion from and withdrawal into the thicker basal portion of the ray-hke distal 

 extremities of the tentacula of this species may be compared to the introversion 

 and extension of the fingers of a glove. The thickened and tubular basal parts, 

 with the fine, ray-like distal portions entirely retracted, are slightly dilated at their 

 free end and present, as shown at a a, in PL XLVIIIa. Fig. 5, an aspect closely 

 resembling the shortened tubular suckers of the ordinary Acinetae. When, on the 

 other hand, the ray-like part is completely everted, the basal part exhibits, as shown 

 in the same figures, a more elongate, conical outline. Two embryos having the 

 surface of their bodies entirely cihated were observed by Claparede and Lach- 

 mann to make their escape from one of the examples that formed the subject of their 

 investigations. 



Genus II. ACTINOCYATHUS, S. K. 

 (Greek, aciin-, ray ; kuathos, a cup.) 



Animalcules solitary, fixed, secreting an indurated pedicellated lorlca ; 

 tentacles more or less retractile, not furnished with suctorial or capitate 

 extremities. 



This genus is herewith instituted for the reception of those infusoria which, 

 while corresponding with Ephelota in individual form and structure, exhibit by their 

 secretion of a membranous sheath or lorica a relationship with that type parallel 

 to that which exists between the respectively loricate and illoricate genera, Acineta 

 and Podophrya. A single species only can at present be referred to this genus, 

 the same being an inhabitant of salt water. 



Actinocyathus cidaris, S. K. Pl. XLVIIIa. Fig. 6. 



Body subspherical, slightly flattened, with numerous and, when partly 

 contracted, thickened muricate or echinulate tentacles, issuing chiefly from 

 the anterior extremity ; lorica cup-shaped or patellate, tapering posteriorly, 

 mounted on a slender, rectilinear pedicle of about three or four times the 

 length of the lorica ; contractile vesicle single or double. Diameter 

 of body 1-650". Hab. — Salt water. 



Three or four examples of this animalcule were met with in February 1878, 

 attached to the external surface of the calcareous sponge Grantia comprcssa, 

 obtained at St. Heliers, Jersey. In none of these specimens, although watched for 

 a considerable interval, were the tentacles seen protruded to a greater extent than is 

 represented in the accompanying figure, though it may be anticipated that their 

 capacity of extension is much more considerable. The body of the zooid, whose 

 height and diameter closely correspond with those of the lorica, is never completely 

 enclosed within this structure, but merely rests upon it with all but the basal portion 

 exposed, in a manner almost identical with that previously described of Achicta 

 patida. Taken separately, indeed, the protective sheaths of these two species 

 present considerable resemblances, the chief point of distinction being the absence 

 in the type now under consideration of the narrow constriction of the pedicle at its 

 point of junction with the lorica that distinguishes the Acineta. This form does 

 not appear to be permanently connected with its lorica, an entirely naked, freely 

 detached zooid having been met with in close vicinity to the attached, loricate 

 examples. It is at the same time possible that this individual represented the newly 

 formed product by fission or gemmation of an ordinary loricated specimen. The 

 specific name proposed for this animalcule bears reference to the likeness to a 

 minute Cidaris presented by the subspherical body, taken in conjunction with the 



