1 2 INTRODUCTION". 



to be " punctate"; when the pores are small it is " punctulate." 

 The shell is usually simple, but in some cases it is strengthened 

 by an internal layer of vesicular tissue, to the constituents of 

 which IJlrich has given the name " cystiphragms." 



Goncecia (the "cistern cells" of Walford). Bryozoites specially 

 modified to serve as marsupia ; as in Entalopliora nididata. PL 

 VIII. Fig. 2. 



Gonocyst. A form of marsupial chamber produced by expan- 

 sions within the zoarium, and not by the modification of a single 

 zooecium ; as in Berenicea parvitubulata. PL IV. Fig. 5. 



Dactylethrce. [From Sa.KTv\r}0pa, a finger-stall.] A name pro- 

 posed for a form of aborted " zocecia," consisting of short caecal 

 tubes, closed externally. They occur, for example, in Terebellaria. 

 (See PI X. Fig. 5.) 



Mesopores. Aborted zoeecia, which are smaller in diameter than 

 the normal zocecia. They occur in the Heteroporidae, etc. (See 

 PL XI. Fig. 3, and Fig. 2/, p. 11.) 



Median tubuli (Ulrich). Minute tubes between the zocecia and 

 the zoarial lamina of some foliate Bryozoa. 



Cancelli. 1 Passages between the zocecia of some genera, as in 

 Lichenopora. They may be definite, closed tubes, in which case 

 they may be regarded as only a variety of median tubuli ; or they 

 may be irregular, loose passages, cavities left between the zocecia, 

 the walls of which do not coincide. 



Acanthopores. Tubular spines found in many Palaeozoic Bryozoa. 

 They arise from tubules which may be seen running along the walls 

 of zooecia. They are typical of the Trepostomata, and may be 

 limited to that order. 



Diaphragms? Transverse plates which cut across the zooecia, 

 either completely or incompletely. (Diaphragms close to the 

 apertures, or the ends of broken zocecia, have been described as 

 opercula.) (Fig. 2d.) 



Cystiphragms. Curved calcareous plates which grow on the 

 tubes of some Bryozoa; they form a vesicular lining round the 

 tube, which is thereby strengthened. (Fig. 2e.) 



1 This term was used by Busk for the structures for which Ulrich' s name of 

 mesopores is here adopted. 



3 This term is also used for the muscular band around the oesophagus in the 

 Cheilostomata. 



