652 R. C. PUNNETT. 
Collar. The musculature of the collar, like that of the proboscis, is somewhat feebly 
developed. The cavity in the anterior part of the collar is very spacious. The intra-collar 
lumen of the csophagus is unusually large (Pl. XLV. fig. 42). The dorsal collar septum 
is present as usual behind the first root. The ventral septum may be found at the hind 
end of the collar or it may be absent. 
TABLE 4. 
Pt. flava, var. gracilis. 










The collar cord exhibits a continuous lumen throughout. 


No. of specimen (1) (2) (3) (4) (5) 
Proboscis coelom.......-...5+.c00s-0- Fairly large Not large as (2) Spacious as (1) 
Collanicoclomisr-e-.s-4s-seereccescene Spacious as (1) as (1) as (1) as (1) 
Ventral proboscis septum......... Nearly to tip as (1) as (1) as (1) as (1) 
of stomochord 
Dorso-ventral proboscis muscles Present as (1) as (1) — = 
| Dorsal collar septum ............... Complete after as (1) as (1) as (1) as (1) 
Ist root 
Ventral collar septum ............ Traces only as (1) Absent as (3) Complete at 
hind end of 
collar 
RACEMOSCIOLPAM! .0c.ccrcc.--eessesces Well marked | Well marked. | Well marked. as (1) as (1) 
but small and | Unlobulated Slightly 
unlobulated lobulated 
Dorsal proboscis muscle decus- Fairly well Not very Well marked. | Very feeble. as (1) 
sation marked. No | marked. No | No ventral cir-| No ventral cir- 
ventral circu- | ventral circu- | cular muscles | cular muscles 
lar muscles lar muscles : 
Worsalll Toobs\scc. -scceccascesseuvs'esdees *RR RRr RRR RRr RRr 4 
IPRODOSCISNPONES IN. ecessesessesenee ses *IR Lr IR IR L only 
INGYVEXCOLG! weecctoescscteesssvaessnes Lumen con- as (1) as (1) as (1) as (1) 
2 me ¥ oa tinuous 
ength of post-brance ial groove ; , ; : ‘ 
- Length of branchial region - au oe ao i te 
Length of cornua x 100 a } ; mee ‘ 
inept oneallan ns es 17-4 19:0 11:3 155 14:1 
coe of branchial ces 1-26 114 1-00 60 85 
Circumference of cesoph. ces. 
Symapiiculaysssss-ssscsscesse-scacccses Not more than} Not more than | Not more than — Not more than 
9 u 7 7 





Three roots 
are usually to 
be found. The cornua of the nuchal skeleton are rather shorter than usual, extending over 
about 1—1 
of the collar length. 
* See foot-note on p. 645. 
