THE ASCARIDES OF MARINE MAMMALS. 107 



The material we had on hand for comparison consisted of a few worms collected 

 in Europe by Stiles and a few bottles found in the Leidy collection. Taking the 

 characters from our own specimens and from the literature upon the subject, the follow- 

 ing key has been prepared and will be of service in determining the known ' ascarides 

 of marine mammals. 



KEY TO THE ASCAEIDES OF MARINE MAMMALS. 



1. Adult forms i 2 



Larval forms which are not developed to a degree permitting the determination of the species; 

 generally with prominent tooth ventral of mouth and with conical spine on the tail. 



A. capsularia (p. 164). 



2. Intermediate lips absent 3 



Intermediate lips present ; 9 



No data at hand concerning intermediate lips - 10 



3. Dentigerous ridge present on lips 4 



One papilla on each ventro-lateral lip, said to bear 6 to 7 teeth ; oesophageal and intestinal caeca 

 apparently absent; second portion of oesophagus usually sigmoid. 



Male : 70 to 90"'"' long ; tail with 7 to 8 pairs of postanal papillae, of which 1 to 4 are near tho 

 tip, 5, 6 + 7, and 8 near the cloaca; left (2.3"'"") spicule longer than right (1.7'""') spicule. 



Female: 80 to 100'"'" long; vulva near the middle of the body. 



Host : Delphinapterus leucas. See also A. simplex (p. 121) A. Kiikenthalii (p. 144). 



Data concerning dentigerous ridge are wanting 8 



4. Dentigerous ridge, single 5 



Dentigerous ridge, double; cuticular bands provided with fine transverse striae. 



Male: 28"'"' long; caudal papillae numerous. 



Female: 57™"' long; vulva? 



Host: Otaria jubata^ Patagonia A. patagonica (p. 143). 



5. Cuticular bands with finer transverse striae ; spicules nearly equal - 6 



Cuticularbands without finer transverse striae, but arranged so as to give a serrate appear- 

 ance to the margin of the worm when seen under the microscope; oesophageal and 

 intestinal caeca absent 7 



6. Lips of nearly equal diameter, but of very difl:'erent outline ; oesophageal caecum may be present or 



absent; intestinal caecum present, long or short. 

 Male : 33 to 70'""' long ; 5 to 6 pairs of praeanal papillae, of which 1, 2, 3 are conical and nearer 



the tip, 3 larger than 2, 2 larger than 1 ; 4, 5, 6 shorter and nearer the cloaca, 5 larger than 



4 or 6. About 60 pairs of praeanal papillae, increasing in size from first to eighth ; spicules 



nearly equal, 1.5 to 2.5"'™ long. 

 Female: 25 to 80™™ long; vulva near middle of the body. 

 Hosts : Phoca, Cystophora, Odobenus, Halichoerus, Callorhinua, Eumetopias ; Arctic Ocean and 



Bering Sea A. decipiens (p. 1091. 



Lips of nearly equal size (Krabbe), or dorsal lip (0.12™™) much smaller than ventral (0.30'"™) 



lip ; oesophageal and intestinal caeca absent. 

 Male: 37 to 130™™ long; 6 to 8 pairs of postanal papillas, of which 1 to 4 nearer the tip, the 



outer pair being longest ; 5 to 8 are shorter and nearer the anus ; praeanal papi,llae arranged 



each side in one or two rows, the first six pairs nearest the cloaca are shortly pedunculate; 



the others are longer; spicules 1.68""™ long. 

 Female : 97 to 200™"" long ; vnlva a little in front of the middle of the body. 

 Hosts: Salaenoptera, Delphinapterus, Monodon, Syperoodon, Lagenorhynohus, Otaria, f Phocaena, 



f Delphinus, f Platanisia ; Greenland, Iceland, Denmark, and elsewhere ..A. simplex (p. 120). 



• Seteroeheilus tunicatus found in Manatua inunguis and PerHrachelius msignis found in Delphinus 

 amazonious (= Inia Geoffroyi) are not considered in this key. From Drasche's studies it seems probable 

 to us that Peritrachelius, type P. insignis, is a synonym of Ascaris, but we liesitate to suppress the genus 

 at present without first examining specimens of it. Seteroeheilus also may be an Ascaris, but we have 

 no specimens for study. See footnote, p. 103. 



