52 F. A. HATI1EK, GRINOIDE A OF GOTLAND. 



full-grown individuals cirri lnay huve been 30 or 40 mm. long. The greatest diameter 

 of a eirral, as observed in a large specimen, is 2 mm. The extreme proximal cirrals are 

 elongate and like flat extensions of the columnals; they widen slightly in the eourse of 

 their length and have Hat backs. Succeeding cirrals gradually become more rounded, and 

 much wider and thicker, with circular seetion. The ossicles in smaller cirri do not become 

 much wider, hut are as long as those of the larger cirri. The axial canal is always large 

 and elongate in the proximal cirrals (Pl. II, figs. 74 — 76); smaller and apparently circular 

 in subsequent cirrals (Pl. II, fig. 77). 



The outer lateral sutures are often härd to detect, especially in the distal region of 

 the stem where the cirrus-groups obscure them (fig. 67). The outer median sutures are 

 0.5 mm. apart: they are very clear in the distal region; how far they extend proximally 

 is unknown, but certainly up to region 4. 



There is a fragment of a large stem, 35 mm. long and about 6 mm. wide (fig. 69). 

 In this the distal portion is evidently not preserved, for there are traces of the cirri be- 

 longing to it. At the 1 5 1 h ossicle from the distal end of this fragment, the distance 

 between the outer median sutures increases slightly, and it continues to increase distal- 

 wärds gradually but irregularly: the portion of the ossicle between the sutures gradually 

 becomes elevated, and then rounded on all its sides, and at last there appears in it a 

 small hole. It is in fäet clear that in the distalmost portion of the stem there were cirri 

 given off along this line. Further, that these cirri were primitive appears to follow from 

 the rudiments above described, which are easily explicable as degenerate cirri, but which 

 can hardly be regarded as nascent cirri. 



The inner median suture can be made ont in sorne specimens of this species (tig. 

 67), and it is curious that there should be the appearance of a faint groove alongside 

 of it, just as there always is alongside of the outer lateral sutures. As to the meaning 

 of this groove, no explanation that bas hitherto suggested itself seems worthy of publication. 



The seetion of the stem at its distal end is almost circular, but is straight-cut where 

 the cirri abut on it and gives off ridges above the cirri (fig. 70). Higher up it is ellip- 

 tical, and probahly becomes round again in the proximal portion (fig. 67). 



Coiling of the stem is produced as before by the different heights of the ossicles on 

 the outer and inner curves. The coil is fairly close (fig. 65). 



This species is primitive in the possession of all 5 sutures, and in the occurrence 

 of a third cirrus in the distal region. The peculiar way in which the cirri appear to 

 spring from the backs of the ossicles resembles the origin of the cirri in H. brachiatus. 

 In other respects the species is remarkably moditied, and totally distinct from all others. 



This species was not figured by Angelin. 



Locality: Specimens a, b, from neighbourhood of Wisby, and specimens < — g from 

 Follingbo, (f). Not known ont of Gotland. 



