54 PHYLUM TUNIC AT A (UROCHORDA). 



Blumenbach, very like Salpa, Th. detnocratica-mucronata Forsk. Pegea 

 Sav., very like Salpa but with supposed traces of stigmata (hemitremata) 

 on its dorsal wall. lasis Sav., like Salpa, but with several embryos at 

 different stages of development in the same sexual animal. 



The abyssal form Octacnerntts Moseley, discovered by the Challenger 

 Expedition and described by Moseley* is placed here ; why, it is difficult to 

 for it does not appear to possess any important salp-like feature. 

 Octacnemus bythiu* .Moseley, body octoradiate, medusa-like, flattened 

 antero-posteriorly, probably attached, test gelatinous, thin, transparent ; 

 pi larynx with no stigmata or openings into the atrial cavity ; digestive 

 'ir-ans coiled up to form with the reproductive organs a nucleus which is 

 pl.ir-ed posteriorly ; S. Pacific. Our knowledge of its structure is limited, 

 .MM! nothing is known about its budding and reproduction. 



A second imperfectly known colonial speciesf O. patagoniensis Metcalfe 

 from 1,000 fms. off the coast of Patagonia has been assigned to this genus. 



Sub-order 2. Cyclomyaria (Doliolida). 



Barrel-shaped Thaliacea with thin test, and pharynx with two 

 rows of stigmata on its posterior watt. The asexual form has a 

 ventral stolon which buds and produces three kinds of zooids, one 

 of which develops sexual organs. The muscular rings are complete 

 ventralli/ and a tailed larva is ahvays developed. 



Doliolum is a transparent pelagic organism with a thin test in 

 \vhich there are no protoplasmic elements and no cellulose. The 

 pharynx (Fig. 46) occupies the anterior part of the body and the 

 atrial cavity the posterior, the digestive canal and the heart (5) 

 together with, in the sexual form, the gonads being aggregated 

 together in an inconspicuous nucleus behind the pharynx on the 

 ventral side of the atrial cavity into which they project. The 

 mouth (1) and atrial (17} openings are at opposite ends of the 

 body and terminal, and the edges of both are lobed. There are 

 no tentacles The dorsal tubercle (22) is surrounded by the 

 spirally coiled, dorsal ends of the peripharyngeal bands, and the 

 pharynx, which has an endostyle (3) but no dorsal lamina, 

 possesses only two rows of stigmata placed in its posterior wall 

 (20). There is a ganglion and closely adjacent subneural gland 

 (21), which opens in front of the peripharyngeal band by the 

 dorsal tubercle (22). The muscular bands of the body-wall are 

 in the form of complete hoops, of which there are nine in the 



Trim*. Linn. Soc. {-). I. p. -_'s7, IX7t'>. See also Herdman Challenger 

 I, 1 ' ports, Timi.-iitM. Pt. Ill, 1888. 

 t Metealfe, Jo////> Hopkins Univ. ('ire., 12. IS't.X Fie. 8. 



