TUHBKLLARIA. 
533 
IV. Cephalothricidce. Commissures of the ganglia separated by a 
distinct antero posterior interval. Lateral nerves placed between the 
longitudinal muscular coat, and an isolated inner band of fibres having 
the same direction. Proboscis with 3 layers (an external circular or 
elastic, an internal longitudinal, and a glandular layer supplied with 
acicular papillge). Circulatory system composed of 2 great longitudinal 
trunks, communicating behind the ganglia and at the tail. Oviparous ; 
the young undergo no distinct metamorphosis, though they have eyes, 
whereas the complete animal is generally eyeless. 
12. CepJialothrix, Orst. Head nearly cylindrical, slightly tapered in 
front ; eyeless, or with a few obscure pigment-specks ; cephalic fissures 
and sacs absent ; mouth situated a considerable distance behind the snout. 
C. linearis^ Rthke., p. 208, pi. iv. figs. 4 & 5. 
(The number of reduced nominal species, referred to as synonymic, is 
in several species so large, that no account could be given of them here). 
Marion (10) doubts the validity of the species of Drepanophorus 
established by Hubrecht [Zool. Rec. xi. p. 501] ; D. spectahilis (Quatref.) 
= Borlasia splendida^ Kef. Marion’s description of the armature of 
the proboscis appears incompatible with that of Hubrecht. Marion 
describes a recurved, granular, yellowish plate borne upon a hyaline 
mass, and furnished with 2 bundles of special muscles ; 9-20 points are 
inserted upon the keel of this plate ; on each side of the bulb are 8-10 
styligerous vesicles, &c. According to the same author (9), the herma- 
phrodite Nemertean occurring in the gill cavity of Phallusia mamillata 
and gelatinosa [Zool. Rec. x. p. 481] does not differ specifically, though 
offering some minor differences, from that found among the Posidonia 
roots {Borlasia hefersteini). 
Tetrastemma elegans (Gir.), Verrill, Am. J. Sci. (3) x. p. 40. 
Amphiporus pulcher (Mull.), Mesostomum bijidum, McI., and Vortex 
capitata, (Orst.), are figured in “ Marine Invertebrates of St. Andrews,” 
pi. iv. fig. 3, and pi. Viii. figs. 3-10. 
Moseley’s (12) new family Pelagonemertidoi is a link betweep Nemer^ 
tea and Planaria dendroccela (as Prostomea between Nemertea and Pt. 
rhabdocoela). “ Animal free swimming, pelagic ; body gelatinous, hyaline, 
broad, and flattened (leaf shaped) ; proboscis unarmed ; no ciliated sacs 
or special sense organs ; digestive tract dendrocoelous.” Pelagonemertes, 
g. n.. Moseley, “ Anterior extremity broad and abrupt, the posterior 
narrowed to a point ; digestive canal with 13 pairs of lateral ramifica- 
tions. Integument thin, with a thin muscular tunic immediately beneath 
it, consisting of external circular and internal longitudinal fibres.” 
P. rollestoni, sp. n., only found twice in deep-sea trawling, at 50° S., 
123® E., 1800 fath., and at 34° 58' N., 139° 30' E., between 155 and 420 
fath. In the proboscis and its sheath, and the nervous and vascular sys- 
tems, Pelagonemertes agrees with the Nemerteans ; the sexes are distinct, 
and the ovaries placed along the lateral vessels ; the ramifications of the 
intestine are developed successively, from before backwards, not planned 
out at once as in young dendrocoelous Planarians. [Lesson’s Pterosoma 
planum is evidently something closely allied, but with a pair of eyes and 
unbranched digestive tube,] . 
