﻿380 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



The nerve cord is slender, less than half the width of muscle 1. 

 Anteriorly the rather slender paraneural muscles arise from muscle 1, 

 4-5 mm. behind nephrostome. The bilobed cerebral ganglion has 

 across the front a prominent frons (cerebral organ) composed of short 

 bushy elements, exactly resembling a very tiny cauliflower. 



Color in alcohol faded 3'^ellowish; the La Paz specimen is gray varied 

 with straw color. 



Type locality. — Esmeraldas, Ecuador. 



Distribution. — Ecuador to La Paz, Baja California. 



Specimens examined. — Four, as follows: 



La Paz, Baja California, Lyman Belding, 1 specimen. 

 Panama, Hassler Expedition, 3 specimens. 



Remarks. — So far as I know there is no record of this species from 

 the region betweeu Panama and La Paz. Its capture at La Paz by 

 Lyman Belding, a pioneer ornithologist of California, illustrates 

 amatem''s luck, for E. F. Ricketts, collecting extensively in that 

 locality in 1940, did not find it. 



Genus SIPHONOSOMA Spengel 



Siphonosonia Spencjel, 1912, p. 264 (type, Si-punculus australis Keferstein). — 

 Gerould, 1913, p. 432.— Fisher, 1950b, p. 805. 



Diagnosis. — Size usually large; body resembling that of Sipunctdus, 

 while head and introvert suggest Goljingia; longitudinal muscle layer 

 always separated into bands, the circular layer into distinct anasto- 

 mosing fascicles (in most species) ; larger species provided with in tegu- 

 mental coelomic sacs (instead of longitudinal canals of Sipunculus) ; 

 four retractor muscles; a simple intestinal spiral anchored posteriorly 

 by spindle muscle, which has tlu-ee anterior roots; only the dorsal 

 contractile vessel present, usually with very many Polian villi; two 

 nephridia with large crescentic nephrostomes ; paraneural muscles of 

 ventral nerve cord less well developed than in Sipunculus, the cord for 

 some distance back of head being fastened to body wall by a mesentery; 

 tentacles filiform, or acute digitiform when contracted, numerous, 

 arranged as in Golfingia, and forming a rather dense cephalic cluster; 

 no conspicuous scalelike papillae on introvert. 



Remarks. — Spengel separated this group from Sipunculus mainly 

 on the basis of the integumental coelomic spaces, longitudinally ar- 

 ranged, which are not continuous, long canals as in Sipunculus but 

 are small blind sacs showing characteristic forms in different species. 

 He pointed to other differences such as the spindle muscle, the large 

 semilunar nephrostome, attachment of nerve cord in anterior part of 

 introvert, the presence of thick glandular epithelium in the wall of 

 the rectum, structure of the tentacles, and the absence of scaleHke 

 papillae on the introvert. Spengel was rather fascinated by the 

 integumental coelomic pouches. While these are fundamental struc- 



