Description of Genera and Speciea. 1 7 



lapping plates with rounded ends and finely ciliated borders. They are very delicate in 

 texture, and are usually much wrinkled in their fossilised condition. The external 

 openings of the genital organs in the male, as already stated, open on a ])apilla situated 

 on the sternal part of the last trunk segment at the base of the limbs (fig. 7'^). The 

 <-audal limbs (figs. 4, 7^^) on the first five tail segments in both sexes are in the form of 

 powerful natatory organs each having a very strong muscular base and terminating 

 in spatulate many-jointed blades set along their edges with strong seta;. As in 

 Gnathopluiusia, these are all uniform, and none of them are specially modified for 

 sexual purposes, although the manner in which the first jjair are applied to the sterna 

 of the trunk in fig. 1^ suggests that they may have assisted in directing the male 

 products to reach the marsupium of the females, as spermatophores are not in use in 

 this group of Schizopods, The uropods on the sixth tail segment are flattened out in 

 the usual manner to act along with the telson as a caudal fan (figs. 1, 3. 4, 5). They 

 consist of a very short and fhittened basal part and two terminal plates, and are 

 <[uite caridean in structurt\ Tlie outer plate is strengthened on its outer margin and 

 terminates in a decided spine, the inner part being more web-like and corrugated and 

 edged with setaj. A transverse suture crosses the plate from the base of the spine, 

 separating it from the terminal lobe, wliich is fringed along its outer margin 

 by strong seta3. When the terminal lobe is broken off, as in fig. 1, the 

 margin of the suture is seen to l)e ciliated with fine seta;. The inner plate is 

 tongue-shaped, keeled near its mid-line, and fringed with setre on both sides as well as 

 round its apex. Both plates seem to be of about the same length, and do not extend 

 backwards as far as the tip of the telson. 



The appendages of the telson, as already stated, consist of flattened lobes fringed 

 with seta3 which are articulated with the telson at the constriction in front of the 

 terminal lol)e, and seem to Ije characteristic of .several of the genera entering' into the 

 family. 



The .specific name is derived from tiie ancient district of Loudonia. Haddingtonshire, 

 being still known as Eastlothian. 



Localit'i/. — All the specimens of this genus are from dark calcareous shales exposed 

 on the seashore near Gullane, Haddingtonshire. 



Honzon. — Wardie Shales, Oil Shale Group, (Scottish) Calciferous Sandstone 

 Series. 



Collector. — A. i\Iacconochie. 



