NEMERTINEA - BAYLTS. 117 



The onlv other puiiit specially olwerved was tlie 'j^wnt ilevelopnieiit. in some 

 specimens, of iiiuseUi-liuinlles miiining througli tlie nelatinons purenchyme in a dorso- 

 ventral direction. These muscles pass through tlie longitudinal muscle-layer, and 

 are connected with the circular muscle-layer dorsally and ventrally. 



'2. .\ii//i/u/ii>r/i.-< niiilfilntsfiifns. Joubin. (I'l. I, tigs. 1, 2, 5, 7, D.) 



Anipliipiinix HiiiUihdstiitiis [Puunett (/?? litt.)\, Jouliin, I'JIO, jiji. 11-12; Text-tigs. l-"i, IG : 

 PI. T, tigs. 7, 8. 



Stations l'i'O, .ilG, 331. 35G : 45-250 fathoms. 



This species appears to he toleral)ly aljundant in and near McMurdo Sound. It 

 was first recorded from Cape Adare. in tlie " Southern Cross " collection, and some 

 of the " Terra Nova " material comes ivum the same locality. The collection contains 

 thirteen specimens and some fragments helouging to this species. As it has been 

 pos.sible to cut some serial sections, and to examine the proboscis carefully, a few 

 points in the structure of the species, which have not previouslv been described. nia\- 

 now Ije noticed, and a few measurements given. 



External Featurk.s. 



The largest sjiecimens measure about 5 cm. in length. Their thickness, according 

 to the state of contraction, is very variable. 



The alimentary canal and proboscis-sheath have a common opening on the head, in 

 the form of a, median vertical slit (PI. I, fig. 2, M.). The external openings of the 

 cerebral organs are in the form of cresceutic slits, mainly transverse in direction (PI. 1, 

 fig. 2, C.S.) Numerous eyes were found to be present; they are situated rather deep 

 in the sulistauce of the head, and are arranged in two lateral ])at<-lies (PI. I, fig. 1, E.). 



Internal Anatomy. 



Aliniciitiirii ('(Hull. — The oesophagus is at first (in the region of the brain) 

 \ery narrow. Soon, however, it expands into a \'oluniinous stomach, with much 

 folded walls. This is succeeded again b\- a narrower pyloric canal (PI. I. fig. 5, 

 Pyl.) which ojieiis into the mid-gut at about 4 mm. (in a spirit specimen, as 

 calculated from .serial sections) from the til) of the head. There is a larse cajcum 

 (PI. I. fig. 5, CW.) extending forwards from this point, \eiitrallv to the pvloric 

 canal, as far as the posterior end of tlie folded stomach, with which it jippears to be in 

 lose contact. This caecum .sends out numerous lateral pockets (PI. I, fig. 5. L.P.), 

 which curve upwards within the muscles of the ])od\-wall. 



/'/■(//» <,sv 7. s-. — The most striking feature of the probo.scis iu this species, as 

 M. .loubin notices, is its very great thickness in proportion to the animal's bodv. Its 

 anterior portion is exceedingly muscular, and its diameter is ab(jut equal to half that 



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