KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 2. 121 



This species was founded by Angelin on two specimens, (o) that figured in Tab. 

 IV, fig. 9, and the other figured specimen, which can ixj longer be found. Fresh 

 information has been gleaned from the following specimens, (b) the arms and ventral tube 

 of a large individual, partly figured by me (op. rit. p. 408, fig. 2), (c) a small, rather 

 worn crown, the tube not shown, (d, c, f, g) four individuals on three slabs, showing arm 

 and stem characters well. 



Description. 



Dorsal cup not unlike that of B. ramosissimus: width at base, in specimen />, 3 

 mm.; extreme width above, from R to TR, 7 mm.; height 6 mm. (figs. 180, 187, 188). 



IBB low, wide, with sides almost parallel. In h thcy are 1.5 mm. high and 2.2 

 mm. wide at the base. 



BB hexagonal and heptagonal as in other species. In b they are 3 mm. high, 2.25 

 mm. wide at the base, and 2.75 mm. wide above. 



RR: the central portion bearing the facet projects, so that the facet, which is at 

 right angles to it, slopes outwards slightly. In b the measurements are, 2.75 mm. from 

 basals to bottom of facet, width above 3.2 mm., width of facet 2 mm. 



R' and x are much as in B. ramosissimus. 



Arms: The ossicles (figs. 184 — 186 and 192, a, b, c) are long and thin, with a eurved 

 back and rather flat sides. In b a secundibrach measures 4 mm. high and 1.75 mm. wide. 

 The ventral groove is broad and deep, and the axial canal is separate from the groove. 

 There is a, verv slight transverse elevation, hardly a ridge, on the articular surfaces. 



The covering-plates are, in their simplest form, pentagonal and regularly altesrnating 

 (tigs. 184 — 186). Sometimes, however, there is a swelling at the inner distal angle of 

 each covering-plate; and this swelling may be developed into a distalward directed spine, 

 which in some cases appears to have become separated from its parent plate by suture 

 (fig. 192). 



The appearance presented by the arm-branching has been well described by Messrs. 

 Wachsmuth and Springer {hx\ ät.). But they were not aware that what they described 

 was merely an appearance and not the real strueture. The latter was first detected in 

 specimens d, <\ f and y, which are preserved in a rather different matrix to the others. 

 These specimens show that the branching does not essentially differ from that of B. ra- 

 mosissimus; but the armlets and their branches spring from the inner side of the axil- 

 laries, so that they are normally directed inwards, and close on one another like the leaves 

 of an acacia.. The consequence of this was that when the animal died and was buried 

 one arm lay över and hid another. The underlying arms are hidden by matrix, which 

 requires to be dissected away, together with the overlying armlets, before the true strue- 

 ture can be seen. It is exceedingly difficult to prepare a portion that shall be capable 

 of being drawn so as to convince the sceptical, and even with the specimens it takes some 

 days to convince oneself (figs. 191, 184, 185). 



Anal Structures: The Ventral sac of this species has also been a stumbling-block 

 to many. As a matter of fact it hardly differs at all from that of large specimens of 

 B. ramosissimus (figs. 180, 182, 183, 187, 188, 189, 190). There is a median dorsal row 



K. Sv. Vet. Aknd. Handl. Band. 25. N:o 2. L6 



