424 INVERTEBRATE MORPHOLOGY. 



2. Subclass Thoracostraca. With carapace covering the whole or a 



part of the thorax ; abdominal segments seven. 



1. Order Schizopoda. Thorax completely covered ; thoracic append- 



ages biranious. Mysis, Euphausia, Siriella. 



2. Order Cumacea. Last four or five thoracic segments not covered 



by the carapace ; eyes sessile or rudimentary. Diastylis, 

 Campylaspis. 



3. Order Stomatopoda. Last three or four thoracic segments not 



covered by the carapace ; eyes stalked ; five maxillipeds. 

 Squilla, Lysiosquilla, Gfonodaetylus. 



4. Order Decapoda. - - Thorax completely covered ; five posterior 



appendages uniramous and three maxillipeds ; otocysts in 

 antennules. 



1. Suborder Macrura. Abdomen usually well developed. Ser- 

 gestes, Lucifer, Penceus, Palcemonetes, Alpheus, Cambarus, 

 Homarus, Eupagurus, Birgus, Hippa. 



2. Suborder Brachyara. Abdomen small and concealed beneath 

 cephalothorax more or less perfectly. Porcellana, Libinia, 

 Callinectes, Platyonychus, Cancer, Pinnotheres, Ocypoda, 

 Gelasimus, Gecarcinus. 



3. Subclass Art7irostraca. No shell or carapace as a rule ; with seven 



(or six) walking-limbs ; eyes sessile. 



1. Order Anisopoda, Carapace slightly developed : fii'st two tho- 



racic segments fused with head ; branchiae on anterior maxilla?. 

 A seudes, Tanais, Anthura. 



2. Order Isopoda.No carapace ; first thoracic segment fused with 



head ; body flattened dorso-ventrally ; branchiae on abdomi- 

 nal appendages. Asellus, Oniscus, Porcellio, Armadillid- 

 ium. Idotea, Sphceroma (free) ; Cymothoa, JEga, Bopyriis, 

 Entoniscus (parasitic). 



3. Order Amphipoda. No carapace, first thoracic segment fused 



with head ; body flattened laterally ; branchi on thoracic 

 appendages. Gammarus, Orcliestia, Corophiiim, Cyamus, 

 Caprella. 



LITERATURE. 



GENERAL. 



H. Milne-Edwards. Histoire Naturelle des Crustaces. Paris, 1834-1840. 



F. Miiller. Fiir Darwin. Leipzig, 1864. 



H. Gerstaecker. ArlJiropoda. Bronn's Klassen und Ordnuugen des Thier- 



reichs, Bd. v. Abth. 1. 1866- (not yet completed). 

 C. Glaus. Untersuchungen zur Erforschung der genealogischen Grundlage des 



Crustaceen-Systems. Wien, 1876. 

 C. Grobben. Die Anlennendrilse der Orustaceen. Arbeiten a. d. Zoolog. lust. 



Wien, in. 1880. 



