or Little-known, Polyzoa. 185 



There is usually a larger avicularium at the base of the 

 zooecium in a bifurcation. In the portion figured it is 

 abnormal, being subcapitate, attached more to the side, and 

 with a stoat conical process growing from one side. It 

 generally differs only from the ordinary form in its larger 

 size. 



Family Reteporid^. 



Retepora Worsleyi, n. sp. Plate II., fig. 2. 



Zoarium small, consisting of slender, dichotomously-divided 

 branches. Zooecia bi-triserial, smooth, or minutely granular, 

 glassy; peristome produced, fiuted, lower lip with a deep 

 notch. In the lateral zooecia the outer edge produced out- 

 wards, and having on its lower margin a sessile, horizontal 

 avicularium, the rostrum terminated by two short, sharp 

 teeth. Posterior surface strongly vibicate, finely granular, 

 and glistening. 



This species, which I have much pleasure in dedicating to 

 Captain Worsley, differs from all the other described 

 JRetepores, in the complete absence of fenestrse or reticula- 

 tion, the branches being very slender, dichotomously divided, 

 and with no attempt at anastomosis. The peristome is 

 largely produced, very distinct, and strongly fluted, with a 

 deep mesian sinus. On the lateral zooecia the outer part is 

 produced in a fringed manner; and there is in the lower lip 

 a horizontal sessile avicularium opening upwards, with the 

 rostrum terminated by two short, sharp denticles, very 

 much in the same manner as is seen in the fenestral avicularia 

 of R. serrata (M'G.) Altogether the species is most interest- 

 ing, as showing the inconstancy of zoarial as compared with 

 zooecial characters, even in a genus in which the zoarial 

 character is usually so strongly marked. 



Family Idmoneid^. 

 Idmonea Gasparensis, n. sp. Plate II., fig. 3. 



Zoarium small, dichotomously divided; zooecia in irregular 

 lines across the branches, usually a central, and one on each 

 side, distinct, punctate; peristome long and projecting 

 forwards, obscurely annulated or annularly and minutely 

 punctate. Posterior surface longitudinally sulcate, and 

 transversely and concentrically rugose; finely punctate; no 

 calcified radical tubes. 



This species presents the general structure of /. Milneana, 

 D'Orb., and /. interjuncta (M'G.), but has very few zooecia. 



