34 Rev. T. Hiiicks on the 



nate and in companies of 2-4, sometimes single and detached ; 

 orifice orbicular, unarmed. Gonocyst an irregular inflation of 

 the surface of the branch, minutelj punctate. 



On shell. 



This form has some points of resemblance to TuhuUpora 

 capitata, mihi ('Annals' for August 1881, "Contributions 

 towards a General History of the Marine Polvzoa"), an Aus- 

 tralian species ; but there are differences in the habit of 

 growth and in some of the details of structure which probably 

 entitle it to a distinct name. The present species is exceed- 

 ingly delicate and of most graceful form. The branches seem 

 to be slightly attached and are commonly free towards the 

 extremities ; the tubes are remarkably slender, and the free 

 portions are horizontally inclined rather than erect. T. per- 

 fragilis bears much resemblance to D'Orbigny's figure of his 

 Idmonea cenomana (Pal. Frang., Terr. Cretacds, vol. v. Atlas, 



Tuhulipora Dawsoni, n. sp. (PI. IX. fig. 5.) 



Zoarium forming a spreading, irregularly shaped, intricate, 

 coral-like mass, composed of many branches, much divided 

 and subdivided dichotomously, which radiate from the point 

 of origin and anastomose freely; branches massive, of consi- 

 derable width, somewhat compressed, flattened in front, ex- 

 panding upwards, bifid or trifid at the extremities (which are 

 cellular), recumbent or suberect, never adnate, but attached by 

 numerous calcareous offsets from the dorsal surface to the shell 

 or stone on which the colony grows. Zooecia arranged (in 

 part) in transverse rows (two to five in each), which slant 

 slightly downwards, connate, with a large suborbicular orifice, 

 increasing in height from the inner side outwards, so as to 

 give a serrated a])]jearance to the edge of the branch ; the rows 

 sometimes extending to the centre of the branch, but not sepa- 

 rated by any distinct mesial line, sometimes (and more com- 

 monly) ranging along the sides, the centre being occupied 

 by many detached cells irregularly distributed, with a subor- 

 bicular orifice, which is usually scarcely raised above the 

 surface ; walls thickly and minutely punctate ; the dorsal sur- 

 face rounded, lineated longitudinally, punctate, often with 

 transverse furrows. 



Common amongst the dredgings ; on shells and stones. 



In this fine species the disposition of the c^Us connately iu 

 transverse rows is very much confined to the sides of the 

 branch, and a striking characteristic is the crowd of scattered 

 cells which very commonly fills the centre. The latter are 



