INFUSORIA. 37 



nles, each of which is providecT with a single cilium. Tlie loricated form, otherwise 

 agreeing with Euglena, is Trachelomonas, common in ponds and bog-water. Asco- 

 (llena differs from tlie last in being sedentary ; from this Colacium differs in the absence 

 of the sheath, and in having a branching pedicle. 



The phosphorescent Noctilucid^ embraces the genera JVoctiluca and ZejHodiscus. 

 JV. mtUaris (Fig. 32) is a large form, visible to the naked eye, found in immense num- 

 bers in the su))erficial watei-s of the ocean, and it is one of the 

 causes of their phosphorescence. It is colorless, spherical, with 

 a meridional groove on one side, at one end of which the mouth 

 is situated. A long, slender, transversely striated tentacle ovcr- 

 liangs the mouth, on one side of which a hard, toothed ridge 

 ]irc)jects; close to one end of this is a vibratile cilium. The 

 prcitoplasm consists of a central mass, with radiating portions 



,. ., -.i ,1 1 »• 1 1 ^1 ■ £ 1 Fig. 32. — Noctilucamiliaris. 



comiectmg it witli the sub-cuticular layer ; there is a lunnel- 



sliaped depression leading into the vacuoled central mass, through which the food passes 

 into the same. The phosphorescence appears to emanate from the layer just under the 

 cuticle ; for it has been observed that as the light gradually fades away on the death of 

 the animal, as when one lias been immersed in alchol, th.at the light finallj- ajipears in a 

 ring around the body, since the observer is looking down upon a thin sjilicrical film of 

 light, imperceptible in the single layer over the middle of the globule ; but at tlie borders, 

 where seen as if on edge, sufficient light is sent forth to make it visible. When disturbed 

 they become more highly luminous, so that a fish, for example, moving through the water 

 where they are abundant shows its luminous sides, and its course is marked out by a 

 path of emerald green light. This form is comparatively common in Euro])ean seas, 

 but has only been found, so far as we are aware, by Mr. C. B. Fuller at Portland, 

 Maine, and by Prof. Hyatt and Mr. Kingsley at Annisquani, Mass. 



Among the second division of this sub-order — viz. mouth-bearing, two flagellate forms 

 — are many interesting and well-known species. The Entomostraca, especially those in 

 piuldles of the forest in spring time, are often loaded down with a green, oval form, 

 which stands singly, or in groups, on short pedicles. On superficial examination it would 

 be easy to mistake it for a Colacium ; but on account of its two flagella during the 

 motile period, its firmer cuticle and its two lateral pigment bands, it has been separated 

 from Colacium as Chlorangitcm stentoriuimi. Whether the flagella remain during the 

 sedentary stage or not has not been determined. In Uvella the animalcules are in 

 colonies, free-swimming, and the flagella are sub-equal. 



Two loricated genera, Epipyxis and Dinobri/on, are unsurpassed in beauty by any 

 of their kindred. The lashes are unequal, and the animal is attached to its vase-shajied 

 lorica by a posterior, contractile fibre ; the individuals of Ep/qnjxis are sessile upon 

 conferva?, while those of Dinohrijon occur in branching chains of lorica i. e. each 

 individual set free by sub-division is attached to the inner margin of the case of the 

 ]iarent. In early summer a species, jn-esumed to be D. sertularia., abounds in the water- 

 supplies of cities along the Great Lakes. 



Sub-Order VII. — Cilio-flagellata. 



The animalcules of the Cilio-flagellata have one or more lash-like flagella, and, in addi- 

 tion, a more or less highly-developed ciliary system, thus indicating a position between 

 the Flagellata proper and the true Ciliata. At first only the Peridinidai were included. 



