GENUS HOPLITOPHR YA. 573 



fragments of the posterior region of the body ; as in many Anoplophryce, the hinder 

 of the two zooids may be four or five times smaller than the anterior one and 

 resembles at first sight a bud-development from the same. 



Hoplitophrya securiformis, Stein. 



Body small, elongate-ovate, flattened and widest anteriorly ; the front 

 margin obliquely truncate, often curved to one side and hatchet-shaped • 

 the anterior region of the ventral surface bearing a slender horny band, 

 which is bent abruptly posteriorly and extends backwards to the centre of 

 the right-hand margin ; contractile vesicles four or five in number, disposed 

 in a line along the left-hand border ; endoplast slender and cord-like, nearly 

 equalling the body in length. Dimensions unrecorded, but smaller than 

 H. secans. 



Hab. — Intestinal tract of Ltimbriculus variegatus. 



Hoplitophrya recurva, Clap. & Lach. sp. Pl, XXVI. Fig. 22. 



Body elongate-ovate, rounded and widest posteriorly ; the anterior ex- 

 tremity pointed, curved to one side, its ventral face bearing a single 

 corneous uncinus ; contractile vesicle elongate, sinuous, extending nearly the 

 entire length of the body ; endoplast ovate, posteriorly situated. Length 

 1-125". 



Hab. — Marine, within the intestinal cavity of Planaria limacina: 

 Norwegian coast. 



As many as thirty or forty zooids of this species were observed by Claparede and 

 Lachmann tenanting a single example of the above-named marine Planarian. It 

 was originally described by these authorities under the name of Opalina recurva. 



Addendum to Opalmidce. 



The organisms described by Claparede under the name of Pachydermon 

 acuminatum^ found in company with Anoplophrya within the seminal receptacles of 

 Clitellio arenariuSy and supposed to most closely resemble Opahnidae with a distinct 

 and thickened cortical layer, are determined by Professor E. Ray Lankester * to be 

 rope-like aggregations of seminal cells. 



Order II. HETEROTRICHA, Stein. 



Animalcules free-swimming or attached, naked or loricate, entirely 

 ciliate; cilia forming two widely distinct systems, those of the general 

 cuticular surface short and fine, those pertaining to the oral region of much 

 larger size, cirrose, and constituting a linear or more or less spiral or 

 circular adoral or peristomal series ; the cortical layer usually highly differ- 

 entiated, and enclosing an even, parallel series of longitudinally disposed 

 muscular fibrillae. 



* " Remarks on Opalina," 'Quarterly Microscopical Journal,' 1870. 



