F. R. Coxcper Reed — Salter's Undescribed Species. 107 



traces of similar ' glands ' on several of the other rings. The whole 

 axis, as well as the lateral lobes, is also ornamented with minute pits. 

 The lateral lobes show seven distinct pairs of pleurae, ending 

 abruptly on the smooth narrow margin, but separated by strongly 

 raised ridges. The surface of each pleura is excavated, and bears 

 a furrow, in front of which the surface is shai'ply ridged up. 

 The furrow is close to and nearly parallel to the posterior 

 edge of the pleura. On the ridge along the anterior edge of the 

 furrow on each pleura, there is a so-called ' cutaneous gland ' 

 situated similarly to those figured by Salter ^ for Ph. caudatus. On 

 the first pleura this gland is near the axis ; on the second it is near 

 the outer extremity ; on the third it is placed half-way along the 

 length of the pleura ; and on the fourth it is near the axis. Those 

 on the fifth, sixth, and seventh pleurae repeat the arrangement of 

 the second, third, and fourth. A few tubercles are also found 

 scattered irregularly over the lateral lobes. The pygidial margin 

 was produced posteriorly into an aculeate mucro, but it is broken 

 off short in our specimen. 



Measokements. 



mm. 



Leugtli of pygidium 22-0 (wmws mucro). 



Width of ditto 24-0 



Width of axis of pygidium (at front end) ... 8-5 



Length of ditto 18-0 



Affinities. — Lindstrom's species Fh. ohlusa,- from the Gotland 

 beds, bears comparison with this variety of Ph. caudatus, but 

 though the furrowing of the glabella is closely similar, the V-shaped 

 arrangement of the tubercles seems to be absent and also the 

 'cutaneous glands' on the pygidium. The true significance and 

 function of these so-called glands is at present unknown, but, if we 

 may presume on our scanty knowledge of these structures to make 

 a suggestion, they appear to be similar to the maculaj on the 

 hypostomes of most trilobites which Lindstrom^ after a detailed 

 study has recently concluded had a visual function. It may be 

 that these pygidial structures were organs of phosphorescence. 



Encrinukus multiplicatus, Salter. (PI. VII, Fig. o.) 

 1873. Encrinurus miiUiplicatuii, Salter: Cat. Camb. Sil. Foss. Woodw. Mus., 



p. 51 {a 226). , ,^ 



1891. EnvriHurus multiplicatus, Salter (Woods) : Cat. Type Foss. ^^ oodw. Mus., 

 p. 144. 

 The original specimen is very imperfect, and consists of only 

 a partially preserved pygidium, so that the description of this 

 species must be somewhat incomplete. It is labelled as having been 

 found in the Middle Bala at Barking, Dent, and is preserved in 

 a tough dark-grey limestone. The pygidium has an elongated and 

 pointed form somewhat like E. miUiiseymeiitatus (Forth), and possesses 



> Salter : Mou. Brit. Trilob. Pal. Soc, 1864, p. 52, woodcuts 11 and 12. 

 2 Ofv. k. Vet. Akad. Forhandl., No. 6, 1885, p. 41, pi. xii, tigs. 3, 4, 7, 8, and 

 pi. xiii, lig-. 1. 



^ Kongl. Svensk. Vet. Akad. Handl., B. 34, No. 8, 1901. 



