304 STDNKY F. HAHMI'IR. 



to the proximal end of the zocBciani, a great part of the cavity 

 of whicli it occnjiies. The two calcareous spines at the sides 

 of the orifice have the effect of keeping the conspicuous 

 epitheca, which invests all parts of the zoarinm, stretched out 

 at some distance from the wall of the flask-shaped zooecinm. 

 The curved lines shown by Busk (1884, pi. xxxii, fig. 3 h) on 

 the sides of the zooecia indicate the edges of the thicker 

 lateral cnlcifiod walls, and are probahl}^ the actual junction of 

 the lateral and frontal walls. Their level corresponds nearly 

 with that of the floor of the compensation-sac, which has 

 parietal muscles. The sac originates with great distinctness 

 as an invagination from the proximal border of the opereulnm. 



Smittia trispinosa, Johnst., var. arborea. Lev.' (fig. 42). 



The specimens here referred to wore sent to me, determined 

 as above, by the Upsala Musenm. Fig. 42 shows that there 

 is a large compensation sac {c s.), the opening of which is 

 overhung by a median lobe of the frontal shield. The 

 condyles [cond.) are at a much deeper level, and are long, 

 recurved denticles, which are crossed by the submarginal 

 lateral sclerites of the operculum. They clearly form the 

 hinge on which that structure moves. I^ypical parietal 

 muscles are present. This form can hardly be regarded as 

 a very typical Smittia. 



Smittia reticnlata," J. MacGillivray (fig. 40). 



My evidence with regard to this species is not complete. 

 In specimens from which the basal wall has been removed I 

 have just been able to detect a large compensation-sac with 

 walls of great tenuity, into which parietal muscles are in- 

 serted. The median denticle [m. /.) or "lyrula"^ appears to 

 belong to the suboral avicularium (as in Rliy nchozoon). 



^ "Brjozocr fia KaralLivet," 'Dijiuplina-Togtets Zool. bot. Udbytte,' ISSfi, 

 p. IG. 



2 nincks(18S0), p. iMO. 



3 Cf. Waters, 'Ann. Mnj:. Nat. Ili&f.' (0). iv, p. It. 



