.- 846 " THETIS " SCIENTIFIC RESULTS. 



- Serlularia minima, Thompson, Ann. Mag. Nat. Hist., (5), iii., 

 1879, p. 104, pi. xvii., tigs. 3, 3rt, 3 J. Id., Bale, Cat. Anstr. 

 Hydroid Zoophytes, 1884, p. 89, pi. iv., figs. 9, 10, pi. xix., 

 figs. 12, 13. Id., Allraan, Journ. Linn. Soc, Zool., xix., 

 1886, p. 138, pi. xiii.,figs. 3, 4. Id., Etheridge, Austr, Mus. 

 Mem., No. 2, 1889, p. 41. Id., Marktanner-Tnrneretscher, 

 Ann. k.k. Hof.-Mus. Wien., v., 1890, p. 231. Id., Thornely, 

 Journ. Linn. Soc, Zool., xxxi., 1908, p. 83. 



. Sertularia pumiloides, Bale, Joui'n. Micro. Soc. Vict., ii., 1882, 

 p. 21, pi. xii., fig. 2. 



Stations 34, 36. 



Trophosome. — The present specimens of this species differ from 

 typical foi-ms in the greater elongation of their internodes, and 



) in the obscurity of the stem nodes, ])articular]y on the lower 

 portion^ of a stem. They thus come to resemble Sertidaria 

 distans, a species to which they are apparently very closely 



.related; but the distinguishing points are to be found in the 

 robustness of build of Sertularia miniraa, the marginal teeth 

 being especially long and strong ; in the comparatively large 

 proportion of the hydrotheca which is adnate to the stem, the 

 small [)roportion which is free ; and in the small proportion of a 

 hydrotheca-pair which is contingent in front of the stem. 



Coughtrey, Bale, and AUman refer to transverse markings in 



V the hydrohiza. They are here well developed in the colonies 

 from both Stations, consisting of ribs of chitin which run verti- 

 cally up the sides of the tubes at irregular intervals, and project 

 across the cavity of the tube for about a quarter of its breadth. 



\ Viewed from above, they appear as piers of chitin running out 

 from the lateral walls and terminating in a hammer-headed knob. 

 Such a type of supporting structure is by no means of definite 



■specific value, however, for in my own experience they occur in 

 the hydrorhizal tubes of species so widely separated as Podocoryne 

 anechinata,^^ Sertidaria heterodonta,'"^ *' and Plumidaria lageni- 



, fera, var. septifera ;^ ° while Warren has described them as char- 

 acteristic of Pasythea quadridentata,^ ^ and Bale (1884, p. 90) 

 says they occur in many species of Plumidaria. It is apparent 

 that such strengthening ribs are analogous developments in very 

 diverse forms, perhaps induced, as I have suggested, where the 



33 Ritchie— Proc. Zool. Soc, 1907, p. 499, pi. 23, fig. 10. 

 3* Ritchie— Trans. Roy. Soc. Edinb., xlvii., 1909, p. 79. 

 ' 3 5 Ritchie— 26id., p. 88, fig. 76. 

 36 Warren— Ann.. Natal Gov. Mus., i., 1908, p. 313, fig. 11. 



