213 
Description of a New Species of Phyllocarid. 
{T)Hymenocarls hepburnensis. Plate XXVIII. 
Description. —Based upon the two specimens figured. 
Casts of the carapace and abdominal segments. Carapace subtri- 
angular, highest towards the front, which is flattened or even slightly 
concave; dorsal margin longest, widely curved, sloping rapidly to the 
posterior margin, which it meets at a sharp angle; the posterior extremity 
narrow and concave. Ventral border short, nearly straight, concave in the 
posterior third. In the mandibular region, in one specimen, there is an 
impression of a stout, elliptical body, which may be the indication of a 
rostral element. Abdominal segments closely conjoined to the body of 
the carapace, widely arched, and consisting of about seven subquadrate 
joints, slightly narrowing to the extremity, which is more or less rounded 
off. No caudal spines seen in the specimens examined. 
Measurements .— Larger example (imperfect). Length, 81 mm. ; height 
of carapace, 35 mm. ; height of carapace at junction with abdominal seg¬ 
ments, 16 nam.; width of lasit segment on specimen, 10.5 mm. 
Smaller example.—Total length, 55 mm. ; length of carapace, 34.5 
mm. ; greatest height of carapace, 22 mm. 
Observations. —This species is provisionally referred to the genus 
Hymenocaris on account of the saddle shape of the carapace and the nearly 
straight posterior margin at the junction with the body segments. Another 
point of relationship with Hymenocaris is the comparatively short and 
curved series of abdominal segments. The rostral body, if such it be, does 
not appear to have been noticed in any examples of Hymenocaris yet 
described; and this feature tends to show a relationship with the Ceratio- 
caridae. It is probable that the discovery of better preserved specimens 
may necessitate the removal of this species to a new genus. 
Hymenocaris is a Cambrian and Lower Ordovician genus in Europe. 
Ceratiocaris ., although typically Silurian, has a few doubtful representa¬ 
tives in the Ordovician. 
The present species is usually abundant in the beds where it occurs, 
some blocks of shale showing on the joint faces layers of these organisms 
distributed along the bedding planes. As is usual with the larger phyllo- 
carids preserved in shale, the form of the carapace is somewhat variable, 
owing to deformation by pressure. 
By the accompanying graptolites, as determined by Dr. T. S. Hall, 
the beds in which this fossil occurs seem to be referable to the upper limit 
of the Bendigonian series. 
Explanation of Plates. 
Plate XXVII. 
Slab of L. Ordovician shale, No. 2404, with Caryocaris marri , Hicks 
and C. wrighti , Salter. About natural size. 
Plate XXVII 1 . 
" w' - - . - - _ , . . • - -." • • 
Fig. 1.—Cotype of ( ?)// ymenocaris Jiepbumensis, sp. nov. No. 1933. 
Jim Crow Creek. 
Fig. 2.—Outline of above specimen. 
Fig. 3.—Second cotype of (?)// ymenocaris hepburnensis, sp. nov. 
No. 1470. Junction of Spring and Jim Crow Creeks. Figures about 
natural size. 
[.Report sent in 13.12.op.] 
