SCALPELLUM 229 



St.WSSo. 14. Hi. 27. 50° 57' 00" S, 63° 37' 30" W. 152-156 m., f.d.s. Gear N 7-T. Some small 

 specimens. N 4-T. One specimen on a Polyzoan. 



St. WS 83. 24. iii. 27. 14 miles S 64° W of George Island, East Falkland Island. 137-129 m., 

 f.gn.s. sh. Gear N 7-T. Three large specimens. OTC. Three small specimens on Hydroids. 



St. WS 84. 24. iii. 27. 7J miles S 9° W of Sea Lion Island, East Falkland Island. 75-74 m., 

 c.s. sh. St. Gear OTC. One large specimen. 



St. WS85. 25. iii. 27. 8 miles S 66° E of Lively Island, East Falkland Island. 79 m. Gear OTC. 

 Two full-grown specimens on Hydroids. 



St. WS 92. 8.iv. 27. 51° 58' 30" S, 65° 01' 00" W. 145-143 m., f.d.s. St. Gear N 7-T. Two 

 specimens. 



Distribution. Pacific Ocean (according to Aurivillius uncertain), Atlantic Ocean 

 south from La Plata, Patagonia, Magellan Strait, Falkland Islands, 18-156 m. This 

 species, rediscovered near the Falkland Islands (Nilsson-Cantell, 1921) is here taken 

 from nine stations grouped round those Islands, where the species seems to be richly 

 represented. From equatorial and northern parts of the ocean no records are known. 



Supplementary Description. This species has already been re-described by Nilsson- 

 Cantell (1921). Since, however, the Discovery collection comes from nine different 

 stations and includes a large number of young stages, some further remarks may be 

 added. These young stages are very richly represented from St. 51. The youngest free 

 stage was a pupa without valves. The metanauplius stage, which is to be found in the 

 mantle cavity as the first development takes place there, has already been described by 

 me as well as the pupa stage (Nilsson-Cantell, 1921). It is re-figured here so as to 

 give a complete series of developmental stages (Fig. i,a). The following young stages are 

 new. In general we know little about the development of ScalpeUum. Broch, who has 

 studied both the species Scalpelhim stroemii (19 12) and S. scalpellum (1924), has added 

 much to our knowledge. A comparison may here be of great interest. 



In a paper on Scalpellids from the coast of Chile (Nilsson-Cantell, 1930) I have 

 discussed some young stages of other species of Scalpelhim, and have found that variability 

 exists in the development of the valves. Broch also noted differences in the order of the 

 appearance of the valves in the pupae of the two species S. stroemii and S. scalpellum. 



The second stage of S. gibberum is represented by a pupa without valves (Fig. i,b), and 

 of this stage I found many individuals. 



The third stage has the primordial valves and all the calcareous plates of the capitulum 

 developed except the rostrum and rostral latera (Fig. i,c). Among all these pupal stages 

 I did not find any with less than eleven capitular valves. According to the theory of 

 Broch there must have been a stage with only five primordial valves, representing an 

 older phylogenetic stage. It is curious that among all these pupae no such form is 

 present. It is possible that intermediate stages may exist, but this does not seem 

 probable, judging from the present material. Variation exists, as is stated also by 

 Broch. 



In the fourth stage (Fig. i, d) the rostrum and rostro-Iaterals appear. In this stage the 

 calcareous plates are developed under and beyond the primordial valves. To the first 



